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10 THE EFFECT OF THE TAX REFORM ACT 

OF 1986 ON COMMERCIAL BANKS 

Thomas S. Neubig and Manin A. Sullivan 

I. INTRODUCfiON 

Before tax reform, several studies concluded that commercial banks had low 

effective tax rates.

1 Thus, banks seemed likely candidates for tax reform. 

and subsequently they have been cited as one of the industries most adversely 

affected by the Tax Reform Act of 1986. Revenue estimates indicate that 

commercial banks will pay an additional $4 billion in taxes over the next five 

years. Like most estimates quoted during tax reform, this figure only 

includes the effects of bank-specific provisions. 

This paper analyzes the overall effect of tax reform on the banking 

industry and shows that the banking industry benefits from tax reform. We 

estimate that as a result of tax reform commercial banks will pay more Federal 

income tax. However. their before-tax income will rise by more than the 

increase in taxes, with the net result of an increase in after-tax income. 

Pre-tax earnings rise because of portfolio shifting from tax-exempt bonds to 

taxable investments. This combined with the reduction in the corporate tax 

rate from 46 percent to 34 percent more than offsets the loss of bank-specific 

tax advantages. 

In this paper, a banking model with individual bank data from 1977 to 1984 

simulates the effects of tax reform on the banking industry. Aggregate tax 

revenue cannot be calculated from aggregated data. A disaggregate model of 

individual banks is necessary because a model using only aggregate data cannot 

calculate the effects of the minimum tax. tax-exempt bond holdings, and the 

amount of the tax bad debt reserves on individual banks. 

The model extrapolates the 14 .400 banks· income statements and balance 

sheets through 1991 and calculates Federal tax liability and after-tax income 

before and after tax reform. The model allows the separate estimation of the 

TIJ~ authors thank Diana Nt!lson for t!~pt!rt programming asswana 111 drl'l.'lopmmt oj'tfrt' ban~

ing mod . Jenny Walrl and Lowell Dworm for tlrerr omm~111s on earlter drafts. and Geraldine 

Huggins for assistance in tlrf! preparation of the manuscript and tables. 

279 
280 Thomas S. Neubig/Martin A. Sullivan 

effects of each of the major tax refonn provisions affecting banks. including 

recapture of existing bad debt reserves and the adjustment to new levels of 

tax-exempt bond holdings. 

The paper has five additional sections. The second section explains the 

tax reform provisions most directly affecting commercial banks. The third and 

fourth sections describe the model and data used for the simulations. The 

fifth section presents the simulation results of the effects of tax reform as 

well as some sensitivity analysis of changes to the key parameters. The final 

section includes a discussion of some limitations of the simulations and some 

future lines of research. 

II. TAX REFORM PROVISIONS AFFECTING 

COMMERCIAL BANKS 

Commercial banks are generally subject to the same tax rules as all other 

corporations. For instance, the corporate rate structure. the alternative 

minimum tax. and the investment tax credit and depreciation rules apply to all 

corporations. Several bank-specific tax rules were changed in tax reform: 

the bad debt reserve deduction. the deduction for interest incurred to carry 

or purchase tax-exempt bonds. the cash method of accounting, and the net 

operating loss carryover rules. In addition. the book income preference of 

the alternative corporate minimum tax will affect many commerciaJ banks 

because book income includes interest from their large holdings of tax-exempt 

bonds. 

A. Bank Specific Provisions 

In this section we look at each of these bank-specific provisions both 

under prior law and under the Tax Reform Act of 1986. 

L. Bad Debt Reserve Deductions 

a. Prior Law 

Under prior law. banks could deduct loan losses using one of three methods: 

the specific charge-off method, the experience reserve method. and the 

percentage of eligible loan reserve method. The specific charge-off method 

pennits deductions when the loans are considered either wholly or partially 

worthless. If part or all of the principal of such a loan is later recovered. 

the amount of the recovery is then included in the bank's taxable income. 

Under the specific charge-off method the bad debt reserve deduction at time t. 

BDRDt. equals the charge-offs ner of recoveries. NCOt . 

For growing firms, the two reserve methods are more advantageous. Under 

the methods. banks are allowed deductions to maintain reserves at the year-end 

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The Effect of Tax Reform on Commercial Banks 281 

allowable level ARt after subtracting net charge-offs against the beginning 

year reserve, Af\_1 • Thus, for both reserve methods bad debt reserve deductions equal additions to allowable reserve plus net charge-offs, as shown in 

equation 10.1. 

(10.1) 

These two methods differ in the determination of allowable reserves, but if 

allowable reserves do not increase, both methods would reduce to the specific 

charge-off method. Allowable bad debt reserves are calculated by specific 

statutory formula. They do not correspond to banks' financial book income 

statement or regulatory bad debt reserves, which are based on the banks' and 

regulators' subjective judgment of the amount of funds necessary to cover 

current and future losses. 

Percentage of Eligible Loan Reserve Method. Under the percentage of 

eligible loan (PEL) reserve method. a bank's allowable reserve equals a 

specified percentage. ht. of its eligible loans. ELt. The bad debt reserve 

deduction equals net charge-offs plus any addition to allowable reserve: 

( 10.2) 

Again, with no change in allowable reserve, this reduces to the specific 

charge-off method. Eligible loans are limited to a bank's total loans less 

loans to financial institutions, FHA and VA insured loans. and commercial 

paper in order to prevent a reserve deduction for loans which have little or 

no default risk. The allowable percentage was J • 8 percent from 1969 to 1975. 

1.2 percent from 1976 to 1981. 1.0 percent in 1982. 0.6 percent in 1983 to 

198 7. The PEL method is scheduled to expire at the end of 198 7. 

2 

An important provision of the PEL reserve method is the base year reserve 

grandfathering rule. Banks using the PEL method are allowed to maintain their 

existing reserve level after a decrease in the allowable percentage of 

eligible loans. This prevents a reduction in a bank's tax reserve which would 

result in inclusion of the reserve decrease in taxable income. For instance. 

a bank can maintain its reserve at I percent of 1982 eligible loans if it is 

higher than 0.6 percent of eligible loans in later years. For banks using the 

base year reserve (i.e.,· those banks with product of allowable percentage and 

eligible loan decreasing), the aJiowable reserve is constant. which leaves the 

PEL method effectively equivalent to the specific charge-off method. Because 

of the declining allowable percentage. a large number of banks were on the 

base year reserve during the late 1970's and mid- I 980's. 

Experience Resen•e Method. Under the experience resen ·e method. the 

allowable bad debt reserve is the product of a bank's six-year moving average 

loan loss rate and its total loans. The experience reserve method was 
282 Thomas S. Neubig. ~artin A. Sullivan 

codified for banks in 1969 and is similar to the six-year moving average 

reserve method (the "Black M0.or Fonnula") allowed for nonfinancial institutions· bad debt reserves before tax refonn. The average Joan loss rate, at. 

is the ratio of actual net charge-offs during the current and preceding five 

years to total outstanding loans during the current and preceding five years. 

The experience method reserve increases if total loans or the loan loss rate 

increases. As under the PEL reserve method. bad debt deductions equal 

increase in allowable reserves plus net charge-offs: 

( 10.3) 

b. Tax Reform 

The Tax Refonn Act repealed both reserve methods for bad debt deductions 

for "large" banks. Banks with more than $500 million in assets (or that are 

part of a consolidated group with more than $500 million in assets) must now 

use the specific charge-off method. "Small" banks may still use the ex perience reserve method and, until it scheduled expiration in 1988, the percentage 

of eligible loan method. 

The bad debt reserve deduction was repealed for nonfinancial institutions 

as well as large banks. The reserve method generally accelerated deductions 

so they are received prior to the year in which the loss would be detennined 

under the "all events test." Thus, bad debt losses were allowed more generous 

tax lreatment than other expected future losses. such as product liability 

claims. Acceleration of future Joss deductions is the equivalent of the 

government making interest-free loans to banks of the amount equal to the 

current tax rate time the amount of the existing tax reserve. 

In addition to the change in bad debt deductions of "large" banks. the Act 

requires the recapture of their existing bad debt reserves into taxable 

income. In general. the recapture of existing tax bad debt reserves recognizes that banks have already deducted amounts added to reserves. If future 

charge-offs are allowed as deductions rather than as nondeductible charges to 

the reserve, then banks would be allowed double deductions for those losses. 

The existing reserve outstanding at the end of 1986 generaJly must be brought 

back into taxable income over 4 years: I 0 percent in 1987. 20 percent in 

1988, 30 percent in 1989. and 40 percent in 1990. The four-year recapture 

rule is thus more generous than requiring future losses to be charged to the 

reserve. which would have recaptured the reserve for most banks in two or 

three years. 

Two exceptions are allowed to the recapture rule. First. "financially 

troubled" banks. which have nonperforrning loans in excess of 75 percent of 

equity capital3

• can suspend the recapture of their existing reserve until 

they no longer meet this definition of financially troubled . Second. a bank 

may elect to include more than ten percenr of its reseiVe balance in 1987 (or 

the first year of recapture). This may be advantageous to a hank with 

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The Effect of Tax Refonn on Commercial Banks 283 

expmng net operating losses or subject to tax credit limitations. The 

remainder of the reseTVe must then be included in taxable income: 2/9th in 

the second year. 3/9th in the third year. and 4/9th in the fourth year. 

The recapture of the existing tax bad debt reseTVes will have a major 

effect on "large" banks' tax liability during the recapture period. Approximate! y 90 percent of the expected tax revenue from repeal of the bad debt 

reseTVe method during fiscal years 1987 through 1991 is due to the recapture 

provision. However. it should be noted that most deductions for increases in 

the bad debt reseTVe were taken at 46 percent. while the recaptured reserves 

are be taxed at only a 34 percent rate. This is the equivalent of the banks 

borrowing $1 from the U.S. government at a zero interest rate and then only 

paying back 74 cents (34/46) upon recapture. 

2. Disallowance of Interest on Debt Used to 

Purchase or Carry Tax-exempt Obligations 

Before 1983. commercial banks deducted all interest paid on deposits and 

other borrowings irrespective of the amount of tax-exempt bonds held. Unlike 

corporations. banks have the ability to tax arbitrage. For example, a bank 

could earn after-tax profits by borrowing $100 at I 0 percent (5 .4 percent 

after-tax at a 46 percent tax rate) and investing in a tax-exempt bond 

yielding only 6 percent. On a pre-tax basis. this transaction results in a 

loss of $4, yet earns $0.40 after-tax. This rule also enabled banks to reduce 

their Federal tax liabmty nearly to zero by holding a small fraction of 

their assets in tax-exempt bonds. 

For tax-exempt bonds acquired after 1982. pre-1986 law disallowed deductions for 20 percent of the interest on debt attributable to the purchase or 

carrying of tax-exempt obligations. The disallowance applied on a pro rata 

basis. If 10 percent of a bank's assets are tax-exempt bonds acquired after 

1982. then 2 percent (I 0 percent times 20 percent) of interest deductions are 

disallowed. 

The Tax Reform Act increases the disallowance percentage to I 00 percent for 

tax-exempt bonds acquired after August 6. 1986. Exceptions are provided for 

public-purpose tax-exempt bonds issued by state and local government entities 

that expect to issue less than $10 million of such bonds during the year. 

Bank purchases of these issues. and bonds related to 20 specific projects 

listed in the Conference Report of the Tax Reform Act. are subject only to the 

20 percent disallowance rule. Previously purchased tax-exempt bonds continue 

to have prior law treatment. 

3. Special Rules for Net Operating Losses of Financial Institutions 

Before the Tax Reform Act. financial institutions were allowed to carry net 

operating losses (NOLs) back to the prior ten taxable years and forward to the 

succeeding five taxable years. This special rule was adopted in 1969 to 
284 Thomas 

S. Neubig/Martin A. Sullivan 

offset the effect of the phasing-down of the percentage of eligible loan bad 

debt reserve method. Nonfinancial corporations were only allowed to carry 

NOLs back 3 years and forward 7 years (15 years after the 1981 Act). The 

longer carryback period increased the likelihood that NOLs could be deducted 

in the current year rather than carried forward into future years. 

Tax refonn requires financial institutions to have the same 3 year carryback and 15 year carryforward rules as all other corporations. However. a 

special transition rule is allowed for commercial banks with NOLs attributable 

to deductions for losses on bad debts. Such NOLs occurring before 1994 can 

continue to be carried back I 0 years. 

B. General Tax Reform Provisions Affecting Commercial Banks 

1 . Corporate Rate Reduction 

Tax refonn reduces the top corporate tax rate from 46 percent to 34 

percent. The new rate schedules are shown in Table 10.1. 

2. Alternative Corporate Minimum Tax 

Under prior law. corporations were potentially subject to an add-on minimum 

tax. Corporations had to pay 15 percent of certain preference items in excess 

of the greater of their regular tax liability or $10.000. in addition to their 

regular tax liability. The only bank-specific preference item was the excess 

of the percentage of eligible loan reserve method deduction over the experience reserve method deduction. By the 1980's most banks were not subject to 

the add-on corporate tax. 

The Tax Reform Act repealed the add-on minimum tax and substituted a broadbased 20 percent alternative corporate minimum tax. The bad debt reserve 

preference item was retained as the excess over the experience method reserve 

Table 10

.1 Corporate Tax Rate 

Prior 1988 and 

Taxable Income Law 1987 Be~ond (percent) 

$25,000 or less 15 15 15 

$25,000-$50.000 18 16.5 15 

$50,000-$75.000 30 27

.5 25 

$75.000-$100.000 40 37 34 

$100.000-$335.000 46 42.5 39 

$335.000-$1.000.000 46 40 34 

$1,000.000-$1.405.000 51 42

.5 34 

Over $1.405.000 46 40 34 

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The Effect of Tax Reform on Commercial Banks 285 

deduction. but will be meaningless for banks after the expiration of the 

percentage of eligible loan reserve method after 1987. However, a number of 

preference items were added. The Act's most important preference item affecting banks is the inclusion of 50 percent of the excess of pre-tax book income 

over alternative minimum taxable income. "Business untaxed reported profits" 

are thus effectively taxed at a I 0 percent tax rate. Tax-exempt interest 

income is the major difference between banks' book income and taxable income. 

No grandfathering of income from existing assets was provided, so banks' 

income from existing holdings of tax-exempt bonds will be subject to this tax. 

To the extent that book bad debt deductions exceed tax bad debt deductions. 

some of the tax-exempt income will continue to be fully sheltered from tax. 

Two other elements of the alternative minimum tax are important to banks. 

First, only 90 percent of foreign tax credits and net operating losses are 

usable against the minimum tax. Amounts disallowed may be carried over to 

other taxable years. Second, minimum tax liability is allowed as a carryforward credit against regular tax liability to the extent attributable to 

deferral items. Minimum tax liability resulting from tax-exempt interest 

income. however, is not allowed as a carryforward credit. 

3. Foreign Tax Credits 

The Tax Reform Act made a number of changes to the foreign tax credit 

rules. Separate limitations for financial services income and interest income 

subject to high withholding taxes were included to prevent the "averaging" of 

domestic and foreign tax rates across different sources of income. Even with 

significant transition rules. over $1 . I billion in additional tax revenues in 

fiscal years 1987-91 are estimated from all corporations due to the separate 

limitation on interest subject to high withholding taxes. 

4 . Umitations on the Use of the Cash Method of Accounting 

After tax reform. use of the cash method of accounting is not allowed for 

taxpayers with average annual gross receipts of $5 million or more. Additional income recognized in the first year from the required change in 

accounting methods must be included in taxable income over a 4-year period. 

5. Investment Tax Credit and Depreciation Rules/Leasing 

Tax reform repealed the investment tax credit and lengthened depreciation 

lives. These changes will affect depreciation deductions for banks' new 

physical assets (bank buildings. computers. etc.). but these account for a 

very small fraction of banks' total assets. A large amount of the banks' 

investment tax credits and depreciation deductions arise from their leasing 

activity. Some of the changes in the after-tax cost of leasing activity will 

be borne by the lessees. 
286 Thomas S. Neubig/Martin A. Sullivan 

III. THE BANK TAX SIMULATION MODEL 

A. Overview of the Model 

The banking model is designed to estimate the tax liability and after-tax 

profit under old law, under the Tax Reform Act of 1986, and under a variety of 

related proposals. There are four basic ingredients to the banking model: 

o the Call Report data~ 

o extrapolation of the Call Report data; 

o the bank tax calculator; and 

o portfolio adjustment from tax-exempt to taxable bonds. 

The banking tax model employs cross-section time-series regulatory 

accounting data. One advantage this data provides is the capability of 

calculating banks' tax bad debt reserves. which is the most controversial of 

all the tax reform provisions affecting banks. Available corporate tax return 

data does not include enough detail nor sufficient years of data to simulate 

effects of changes in allowable tax bad debt reserves. To calculate the 

percentage of eligible loan method reserve, FHA and VA real estate loans and 

loans to financial institutions are subtracted from total outstanding loans. 

To calculate the experience method bad debt reserve deduction in any year, 

data from the current and six previous years are required. Thus, to calculate 

the 1986 experience method reserve, data series beginning in 1980 are 

needed. 

Several other new provisions cannot be estimated directly from tax data 

since relevant information had no bearing in the calculation of past tax 

liability. Book income. necessary for calculation of the new alternative 

minimum tax. was not recorded on tax returns. nor was tax-exempt income 

reliably reported. Both of these data items are directly available from book 

accounting data. 

Due to the efforts of the industry's many regulators and unlike most other 

industries, consistent annual accounting data on nearly aU firms is available 

for the banking sector. Our data set consisted of individual bank data for 

1977 through 1984, the most recent available. These data are extended to 1985 

and 1986 by extrapolating all variables from 1984 levels at the same rate as 

the industry's asset growth. Individual bank data is then extrapolated beyond 

1986 at the same rate as forecast eo nominal GNP. 

The extrapolated individual bank data are used to calculate taxable income 

and alternative minimum taxable income. The first step in arriving at taxable 

income is the removal of state and local taxes and tax

-exempt interest income 

from book income. The book provision for loan losses is added to book income. 

and estimated tax deductions for loan losses are subtracted. Most of these 

deductions are actual charge-offs and are directly available from the data. 

The remainder of the deductions are the addition to tax bad debt reserve. 

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The Effect of Tax Refonn on Commercial Banks 287 

Both the experience method and percentage of eligible loan method reserves are 

calculated for each bank and the largest is assumed to be the bank's chosen 

reserve. 

For most large banks, no bad debt reserve deductions are allowed after 

1986, and the outstanding tax reserve at the end of J 986 must be included in 

taxable income over the next four years. To calculate minimum taxable income, 

specified preference income and one-half of book income net of state and local 

taxes is added to taxable income. For each bank the graduated rate structure 

is applied to taxable income to arrive at regular tax liability and minimum 

taxable income is multiplied by 20 percent to arrive at alternative minimum 

tax liability. The greater of the two determines the bank's tax bill. 

Banks currently have large tax-exempt holdings,4 but lower tax rates and 

the total disallowance of deductions of interest to carry tax-exempts under 

tax reform are expected to virtually eliminate all new purchases of tax-exempt 

bonds by banks. Thus. in the tax reform simulations. banks' holdings of 

tax-exempt bonds are assumed to decline with a corresponding increase in 

investment in taxable assets. As taxable income replaces tax-exempt income, a 

large increase in tax liability occurs from this portfolio shifting. However. 

the negative effect of higher taxes on after-tax income is offset by the 

higher before-tax yields on taxable investments. 

B. Call Report Data 

Reports of Conditions and Income (Call Reports) must be filed by all banks 

that are either members of the Federal Reserve System. insured by the part of 

a bank holding company. or borrow at the Fed's discount window. The reports 

include detailed data on loans. loan commitments. securities, deposits. as 

well as general balance sheet and income statement data. These individual 

bank data are stored on magnetic tape by the Federal Reserve; aggregations of 

these data are published annually in the FDIC's Statistics on Banking. The 

commercial bank. tax simulation model uses Call Report data for over 16.000 

banks from 1977 to I 984. 

There are, however, several disadvantages to using Call Report data to 

analyze the effect of tax reform. lnfonnation about foreign tax credits. 

investment tax credits, and tax depreciation are not available from the CaJI 

Reports. The investment tax credit and accelerated depreciation. which 

account for most of the discrepancy between statutory and effective tax rates 

for nonfinancial corporations. play a relatively minor role in the taxation of 

financial institutions. The omission of foreign tax credits is more serious. 

particularly for large banks. 

An additional shortcoming is that many banks calculate taxes on a consolidated basis. Thus. income of groups of banks as well as nonbank businesses 

are consolidated on the same return. Call Reports. on the other hand. are 

prepared for regulators on an individuaJ bank basis. To the extent that one 

bank's income is sheltered by losses of another bank or other businesses 
288 Thomas S. Neubig/Martin A. Sullivan 

within a consolidated group, revenues calculated from Call Report data are 

overstated. A consolidated Call Report file. in which individual banks in a 

consolidated group are aggregated. was not available in time for this study. 

Even then, members of consolidated groups may eJect to file separate returns. 

C. Model Calibration 

Despite the pains taken to reconcile book and taxable income, many adjustments necessary to achieve this goal could not be directly modeled because of 

incompleteness of the data. The resulting discrepancies between book and 

taxable income occur for several reasons. First, income from nonbank activities not reported to regulators are reported on the tax returns of banks that 

file consoJidated returns with nonbank affiliates. Secondly, not all adjustments to book expenses to correct for larger corresponding tax deductions 

could be incorporated into the model. For example, the excess of tax over 

book depreciation deductions should be included in total tax deductions. 

Finally. as stated previously. banks file regulatory reports on an unconsolidated basis but may file tax returns with holding company affiliates. Thus. 

some banks may be able to shelter positive taxable income by filing a consolidated return with a bank that has losses. For all these reasons. it is not 

unexpected that taxable income computed by the model is different from that 

reported on tax returns. 

These shortcomings do not greatly affect estimates of changes in bankspecific provisions. However. they are crucial in the estimations of the 

level of tax revenue and general tax provisions which depend on level of 

taxable income-namely. rate reduction and the alternative minimum tax. 

Unadjusted model estimates overstate the benefit to banks of rate reduction 

and underestimate the negative impact of the alternative minimum tax. 

A two-step adjustment procedure has been employed to avoid these biases. 

Basically. this procedure attempts to reconcile model output to actual SOl 

data for the years 1980 through 1983, the latest year of aggregate tax return 

data available for this study. The average ratio of model to SOl total 

receipts from 1980 to 1983 is 

1.21 and the corresponding average model to SOl 

total expense ratio is 1.27. 5 For the first-stage adjustment, total receipts 

and total expenses are multiplied by these factors. This eliminates the 

non-bank income and book/tax- accounting discrepancies described above. 

When the model is run with these first-stage adjustments. although taxable 

income totals are substantially reduced. they remain above corresponding SOl 

figures for the 1980- 1983 period. The remaining difference is due to joint 

filing of tax returns by profitable banks with banks reporting negative 

taxable income. This consolidation effect is not reflected in gross receipts 

or expenses. A correction to this model which uses unconsolidated data can be 

incorporated by adjustment to net taxable income. The average ratio of SOl 

taxable income to first-stage model taxable income for the I 980-83 period is 

0.86. Accordingly. the second-stage model adjustment has taxable income for 

all banks multiplied by 

0.86. 

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The Effect of Tax Reform on Commercial Banks 289 

D. Extrapolation of Data 

To extrapolate individual bank data to 1985 and 1986, most balance sheet 

and income statement items were increased from their 1984 levels by the 

industry's asset growth rate for 1985 and 1986. For 1987 through 1991 , data 

was extrapolated by applying the Administration forecast of the growth of 

nominal GNP. 6 The growth rates applied to most data items for 1985 through 

1992 are shown in the first line of Table 10.2. Extrapolations of charge-offs 

for loan losses, tax-exempt bond holdings. and tax-exempt interest income 

receive special treatment and are described below. 

The calculation of the experience method reserve (and, therefore. the 

revenue effect of its repeal) is dependant upon to assumptions about future 

loan losses. Using unpublished FDIC data for 1985 and 1986, this growth rate 

of industry loan losses was assumed for individual banks. Industry or 

regulatory agency forecasts of future aggregate loan losses were not available. Loan losses depend on factors difficult to predict: the health of the 

agriculture and energy sectors; real estate values; whether poorly-performing 

loans to foreign governments will be charged-off; and unforeseen declines in 

other sectors. The baseline loan loss assumption predicts that the loan loss 

rate will return to pre-1980 levels. More pessimistic assumptions are evaluated in the sensitivity analysis in Section IV. All loan loss assumptions 

used are shown in the second panel of Table 10.2. . 

Historical experience as well as accounting relationships suggest a strong 

positive correlation between loan losses and the book accounting provision for 

loan losses. Thus, variation in loan losses generates variations in book 

provision for loan losses. Individual banks' provision for loan losses are 

assumed to equal 1.29 of their net charge-offs based on a linear least-squares 

regression of 1976-84 aggregate loan loss experience on net charge-offs. 

Assumed percentage changes in bank holdings of tax-exempt securities are 

shown in the third panel of Table 10.2. As will be explained in detail in 

Table 10.2 Extrapolation Assumptions Used in 

Banking Model Simulations 

Calendar Year 1985 1986 1987 1988 1989 I 990 I 991 

(Percent) 

Baseline Growth Rate 8.9 3.3 6.5 7.2 7.2 6.9 6.4 

Loan Loss Rate 

Baseline .709 .828 .700 .600 .500 .400 .300 

Static .709 .828 .828 .828 .828 .828 .828 

Pessimistic .709 .850 .900 .900 .900 .900 .900 

Change in Tax-Exempt 

Bond Holdings With 

Portfolio Adjustment -21 .5 -15.2 -27.3 -25.6 -22.5 - 18.7 -16.0 
290 Thomas 

S. Neubig/Martin A. Sullivan 

Section III.F. large increases in bank holdings of tax-exempt bonds occurred 

at the end of 1985 in anticipation of tax refonn, and a steady decline in 

their holdings are predicted after 1986. Total assets are still assumed to 

grow at the forecasted rate of GNP growth. but the composition of bank 

portfolios are allowed to change as a result of tax refonn. Reduced holdings 

of tax-exempt bonds are mirrored by increased holdings of taxable securities. 

E. Modeling of Tax Provisions 

The bank tax simulation model estimates the tax liability and after-tax 

income of each commercial bank in the United States and sums these figures to 

estimate revenue. Several adjustments are made to book net income to arrive 

at regular taxable income and alternative minimum taxable income. First. taxexempt income and state and local taxes are both subtracted from book income. 

Then the difference between a bank's book provision for loan losses and its 

the estimated tax bad debt reserve deduction is added. Finally. the graduated 

rate structure is applied to estimated regular taxable income of each bank and 

compared to 20 percent of the estimated alternative minimum taxable income. 

The larger amount is the bank's estimated tax liability. 

I. Assignment of Tax Bad Debt Accounting Methods to Individual Banks 

Before J 987 all commercial banks could use one of three methods for 

calculating bad debt deductions: the specific charge-off method, the percentage of eligible loans reserve method. or the experience reserve method. Banks 

were pennitted to switch between the experience reserve method and percentage 

of eligible loans reserve method from year to year. Furthermore. banks were 

not required to reduce their bad debt reserve balance below a base year 

reserve as long as totaJ loans outstanding did not decline. Until 1987. the 

base year reserve for each bank is its reserve in the last year 

it adopted the 

experience method: after I 988. the base year reserve is the I 987 reserve 

calculated under either method. The model assumes that each bank uses the 

method which provides the largest tax reserve. 

7 

Table 10.3 Estimated Use of the 

Experience Bad Debt Reserve Method 

Calendar Year 1977 1981 

1982 1983 1984 1985 1986 

Number·of Banks 294 376 679 1.382 2.605 3.755 4.377 

Percent of Banks 

2.0 2.6 4.7 

9.6 18.0 26.0 30.3 

Percent of Bank Assets 1.1 1.1 1.7 

5.0 10.0 19.2 23.3 

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The Effect of Tax Refonn on Commercial Banks 29 J 

In the late 1970's and early I 980's. as the allowable percentage of 

eligible loans was phased down and as bank loan losses mounted, the model 

estimates that an increasing percentage of banks elected the experience 

method. As indicated in Table 10.3. only 2 percent of banks were estimated. 

As a result of tax reform. individua.l banks (or banks part of a consolidated 

group with more than $500 million in assets) are no longer allowed to include 

increases in their tax reserve as part of their bad debt deduction.' Tax 

deductions for loan losses, however. still result as specific charge-offs 

occur. Figure 10.1 shows the relationship between charge-offs and estimated 

tax bad debt deductions. The difference between the two, additions to tax bad 

debt reserve, have consistently been a small fraction of the total deduction 

for bad debts. For example. in J 984. only 5 percent. or $600 million, of 

$I I .4 billion of estimated deductions for bad debt was attributable to use of 

the reserve methods; the other $10.8 billion was due to specific charge-offs. 

2. Recapture of Existing Tax Bad Debt Reserve 

Paralleling its treatment of the repeal of the reserve method, the model 

designates banks "large" (and therefore required to recapture existing tax bad 

debt reserves) only on the basis of individual bank asset size. For most 

banks with over $500 million in assets, I 0 percent of their outstanding tax 

reserves at the end of 1986 are included in 1987 taxable income, 20 percent in 

Figure 10.1 Commercial Bank Actual Net Charge-Off's and 

Estimated Tax Bad Debt Deductions, 1978-1984 

5,000 

- Actual Charge·offs 

•••• Bad Debt Deductions 

•• 

••••••••••• 

••• ••• ....----r 

·············· ~ 

•• •• •• 
292 Thomas S. Neubig/Martin A. Sullivan 

1988, 30 percent in 1989, and 40 percent in 1990. If a bank's growth causes 

its assets to exceed $500 million in any year starting after 1987, then I 0 

percent of its tax reserve are recaptured in that year with 20, 30, and 40 

percent recaptured in the following years. Due to lack of data on nonperfonning loans the exception that allows "troubled" banks to defer recapture 

is not included in these simulations. 

The Tax Refonn Act allows large banks the choice of recapturing more than 

10 percent of the existing tax reserve in the first year. Since it would be 

advantageous for a bank to shelter recaptured income with net operating 

losses. the model assumes that a bank accelerates recapture in 1987 (or its 

first year of recapture) if inclusion of 10 percent of tax reserve still 

leaves the bank with negative taxable income. For the following three years. 

banks taking accelerated recapture, in accordance with the Tax Refonn Act. 

include 2/9's. 3/9's. and 4/9's of their remaining tax reserve in income. 

3. The Corporate Alternative Minimum Tax 

Tax refonn replaces the corporate add-on minimum tax with an alternative 

minimum tax (AMT). Alternative minimum tax liability is generally due to the 

extent it is in excess of regular tax liability. A minimum tax rate of twenty 

percent is applied to the minimum tax base that includes regular taxable 

income (TI). specified tax preferences (PR). and one-half of business untaxed 

reported profits: 

Tentative Minimum Tax = 0.2 * [ Tl + PR + 0.5*BURP 1 (10.4) 

where BURP is the excess of book income. net of state and local taxes. over 

regular taxable income and minimum tax preference items. The only preference 

income other than BURP included is the excess of bad debt reserve deductions 

over deductions allowable under the experience reserve method. which is only 

relevant for small banks in 1987. In the model, business unreported profits 

consist entirely of tax-exempt interest and the difference between tax bad 

debt deductions and book provision for Joan losses. 

F. Bank Portfolio Reallocation to Taxable Securities 

For banks paying the regular tax at rate u and not subject to the alternative minimum tax. the net after-tax interest advantage of tax-exempt bonds 

compared to taxable securities is: 

i - (1 -u)*i - u* b *r • t ( 10.5) 

where ie is the tax-exempt rate ratl!. it is the rate on alternative taxable 

bank investments. b is the nondeductible percentage of interest expense 

attributable to carrying tax-exempts. and r is average interest rate on all 

bank interest-bearing liabilities. 

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The Effect of Tax Reform on Commercial Banks 293 

Banks find tax-exempt bonds more attractive: 

o the higher the tax-exempt interest rate, i.; 

o the lower the rate on alternative assets. it: 

o the lower the average interest expense. r; 

o the lower the proportion of interest which is nondeductible. b; 

o the greater the corporate tax rate. u. 

Tax reform repeals the deductibility of interest used to carry newly 

purchased tax-exempt bonds and lowers the top statutory corporate tax rate 

from 46 to 34 percent. Both changes make tax-exempt bonds Jess attractive 

relative to taxable investments. Banks prefer taxables to tax-exempts by a 

wide margin with these two changes in effect. Tax-exempt rates relative to 

taxable rates must rise far in excess of their historical levels for banks to 

purchase new tax-exempt securities. 

Tax-exempt bonds are even less attractive investments for banks facing the 

alternative minimum tax. For banks subject to the alternative minimum tax. 

the net after-tax interest advantage of tax-exempt bonds compared to taxable 

securities is: 

0.9*i. - 0.8*it - 0.2*b*r ( 10.6) 

The I 00 percent disallowance of interest attributable to tax-exempt securities. the 10 percent minimum tax on tax-exempt interest income, and the lower 

marginal tax rate each reduce the incentive for new purchases of tax-exempt 

securities by banks. 

This analysis suggests that. except for qualified small issues, banks will 

not make new purchases of tax-exempt securities. Furthermore. banks wiiJ not 

sell tax-exempt bonds purchased before August 7. 1986. Despite lower tax 

rates. bonds purchased before tax reform remain a good deal. When old 

securities mature. banks will replace them with taxable investments. 

In addition, tax reform had anticipation effects on bank purchases of taxexempt securities. The tax law prompted banks to purchase extra tax-exempts 

before they lost their special tax treatment. The House tax reform bill 

slated the new law to take effect January l. I 986. During December of 1985 

commercial banks increased their tax-exempt bond holdings by approximately 20 

percent. The exception for new purchases of bonds supplied by small-issuers 

and special projects combined with these eleventh hour purchases considerably 

dampened the aggregate effect of the I 00 percent disallowance rule. Preliminary estimates indicate that the supply of qualified bonds will equal roughly 

20 percent of what bank demand for tax-exempt bonds would have been without 

the I 00 percent disallowance rule. 

In simulations of tax reform. all banks' tax-exempt bonds holdings are 

reduced by the same percentage. shown in Table 10.2. 9 Then. to maintain 

balance sheet consistency for each bank. taxable investments are increased by 

exactly the decline in tax-exempt bonds. Figure 10.2 shows the banking 
294 Thomas S. Neubig/Manin A. Sullivan 

industry's tax -exempt bond holdings in 1984 and 1985 and estimates for later 

years under three different scenarios. Line ( 1) represents the expected 

growth of bank holdings of tax-exempt securities with no changes in the tax 

law. The jump at the end of 1985 depicted in lines (2) and (3) represents the 

actual increase in the holdings of tax-exempt securities by banks. presumably 

in response to an anticipated January I, 1986 effective date for the new tax 

law. To estimate retirements of banks' August 1986, infonnation on the 

maturity structure of banks tax-exempt bond holdings was used. Line (3) shows 

the industry's holdings decline with maturation of existing bonds and without 

any purchases of qualified small issues. Beginning at the end of 1986. line 

(2) shows the decline in tax-exempt holdings which include bank purchases of 

'qualified' smaJJ issues. Line (2). taking into account extra purchases at 

the end of 1985 and new purchases of bonds from small issuers after 1986. 

represents the portfolio shifting in the simulations of tax refonn.10 

IV. SIMULATION RESULTS 

The banking model was used to simulate the changes in banks· Federal tax 

liability and after-tax income from 1987 through 1991 due to the revisions 

most affecting banks. The overall effect of tax refonn is an increase of $5.3 

Figure 10.2 Commercial Bank Holdings of 

Tax-Exempt Loans and Securities 

$Billions 

250 

225 

200 

175 

..-.---~-

. "~ 

·~A 

··~ .. ' 

.. ' 

.. ' 

.. ' 

125 - Without portfolio shifting 

- - Shifting with small-Issuer exception 

100 ••••• Shifting without small-Issuer exception 

.. .. ' ..... .. ~--­ .... ---~ ... -.. ..... .. •• --- •• •• •• 

75~------~--------~--------~------~--------~ 

Dec 84 Dec 85 Dec 86 Dec 87 Dec 88 Dec 89 

Assumes "qualified" issues are 20 percent of new issues purchased by banks with no portfolio 

shifting. Runoffs of new and existing issues are based on maturity structure of 1982 tax· 

exempt holdings. 

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The Effect of Tax Refonn on Commercial Banks 295 

billion over the five year period in the Federal income tax liability of 

commercial banks. Nevertheless, banks are net "winners" from tax refonn. 

Despite their paying more Federal taxes. after-tax income increases by over 

$6. l billion over five years due to rate reduction and higher pre-tax incomes 

from altered investment portfolios. 

The model examines five major changes in the tax Jaw and their interactions. The two general corporate tax changes are varied from column to 

column in Table 10.4: (a) the new rate structure and (b) the new alternative 

minimum tax. Three banking- specific changes and combinations thereof are 

varied from row to row: ( 1) the repeal of the bad debt reserve method for 

large banks. (2) the recapture of existing bad debt reserves into taxable 

income for large banks, and (3) the disallowance of deductibility of interest 

to carry tax-exempt securities. 

A. General Corporate Provisions 

The primary benefit of tax refonn to banks is rate reduction. The reduction of the top corporate rate from 46 to 34 percent by itself would reduce 

Table 10.4 Effect of Tax Reform Provisions on 

Banks' Federal Tax Liability and After-Tax Income 

Between 1987 and 1991, Total 5-Year Changes· 

Without Alternative With Alternative 

Minimum Tax Minimum Tax 

46% Rate 34% Rate 46% Rate 34% Rate 

($Billions) 

(0) Changes Only in Regular Tax Rate and/or Minimum Tax 

Revenue 0 -5.76 1.59 

After-tax Income 0 5. 76 -1.59 

(I) Repeal of Bad Debt Reserve Method 

Revenue 0.03 -5.73 

After-tax Income -0.03 5. 73 

(2) Recapture of Bad Debt Reserve 

1.61 

-1.61 

-3.69 

3.69 

-3.67 

3.67 

Revenue 2.84 -3.66 3.35 -1.90 

After-tax Income -2.84 3.66 -3.35 1.90 

(3) Disallow Deductibility of Interest Allocable to Tax-Exempt Bonds 

Revenue 11.83 3.08 11.86 3. 14 

After-tax Income -0.17 8.58 -0.20 8.52 

(4) Changes (1), (2), and (3) Combined 

Revenue 15.09 

After-tax Income -3.43 

5.49 

6. 17 

15. II 

-3.45 

5.53 

6.13 

• Except for the second and third columns of Row (0) and the first column of Rows (I) to (3). 

these figures represent changes from current law due to combinations of tax law changes. 
296 Thomas S. Neubig/Martin A. Sullivan 

commercial bank taxes by $5.8 billion over the first five years of tax reform. 

Besides this direct benefit to banks. rate reduction lessens the impact of tax 

reform base-broadening measures. because each additional dollar of taxable 

income yields 34 instead of 46 cents in revenue. In the following sections. 

the benefits of rate reduction are weighed against the base-broadening 

provisions which raise bank tax liabilities. 

The effects of the alternative minimum tax ( AMT) can be observed by 

comparing the first and third columns and the second and fourth columns in 

Table 10.4. With no base broadening. the AMT increases tax liabilities by 

$1.6 billion under the pre-tax reform rate structure and $1.9 billion dollars 

with lower rates during 1987 through 1991 . 

The alternative minimum tax for banks is largely a function of the difference between book and taxable income because banks do not have a large amount 

of preference income. Recapture and repeal of the bad debt reserve method 

increase taxable income do not significantly reduce the alternative minimum 

tax. However, the large amount of portfolio switching to taxable securities, 

which increases taxable income by more than it increases book income, reduces 

much of the potential impact of the alternative minimum tax on banks. Once 

banks shift their portfolios toward more taxable securities few banks will 

have minimum tax liability. This is consistent with our earlier assertion 

that banks maximize after-tax income by holding enough taxable securities so 

that regular tax liability equals minimum tax liability. 

B. Provisions Specific to Banking 

By comparing rows (0) and (I) in Table I 0.4 it can be seen that repeal of 

the bad debt reserve method for large banks increases taxes by less than $0.1 

billion under the new rate structure. The effect is small since the banks 

will continue to deduct net charge-offs which have been about 95 percent of 

tax bad debt deductions. Excess bad debt deductions have been reduced due to 

the phasedown and future expiration of the percentage of eligible loans method 

and the base year grandfathering rule which put many banks or the equivalent 

of the specific charge-off method. 

The revenue impact of the recapture of large banks' existing tax bad debt 

reserves can be calculated by comparing rows (0) and (2) of Table 10.4. Under 

lower rates, recapture increase banks· tax liability increases by $1.8 billion 

over the five year period. An important distinction to make between the 

repeal of bad debt reserve methods and recapture is that the former is a 

permanent change while most of the revenue impact of recapture takes place 

during the 1987-1990 period. 

The effects of commercial banks' shifting from tax-exempt to taxable securities due to the disallowance of interest for carrying tax-exempt securities 

can be calculated by comparing rows (0) and (3) in Table 10.4. Under new 

rates and the alternative minimum tax. portfolio shifting increases bank taxes 

by $6.7 billion. Nevertheless. after-tax income increases by $4.8 billion.

11 

How is it possible that banks pay more taxes yet will still be better off? 

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The Effect of Tax Reform on Commercial Banks 297 

The switch to taxables is induced primarily by two factors: rate reduction 

and the disallowance of interest expense. However, although both these 

changes have the same behavioral effect, they have opposite impacts on the 

banks' bottom line. A switch to taxables will increase banks' taxable income 

and thus tax liability, but because taxable investments have higher yields 

than tax-exempt bonds. banks' extra tax burden is offset by higher pre-tax 

yields. This explains why tax increases are greater than reductions in aftertax income. However. with rate reduction after-tax yields on taxables may 

exceed tax-exempt yields and the portfolio switching would increase after-tax 

income. 

The interest disallowance causes banks to switch to taxable investments, 

increases tax Liability, and reduces after-tax income (first and third columns 

in row (3) in Table 10.4). This occurs because after-tax returns from taxable 

investments at a 46 percent rate are lower than tax-exempt yields. Rate 

reduction increases after-tax returns from taxable securities so that when 

banks switch to taxables and increase their taxes. banks could experience an 

increase in after-tax income assuming the implicit tax rate remains constant 

at 33 percent on tax-exempt bonds acquired in the future, as can be seen in 

the second and fourth columns in row (3) of Table 10.4. 

C. The Effects of Tax Reform over Time and 

on Small and Large Banks 

The $5.5 billion in additional tax revenue shown in the lower right comer 

of Table I 0.4 is not evenly spread over the 1987-91 period. The last panel of 

Table 10.5 shows that tax reform lowers the banking industry's tax liabilities 

by $0.4 billion in 1987. Taxes increase after 1987 as banks increase their 

purchases of taxable investments; by 1991 banks have an additional $12.6 

billion of taxable income due to portfolio shifting. Taxes also tend to rise 

from 1987 to 1990 as the percentage recapture of existing bad debt reserves 

increases.

12 Thus. relative to prior law. taxes rise from 1987 through 1990. 

drop in 199 J with the decline in recapture, and then resume their rise as 

banks continue to substitute taxab1es for maturing tax-exempts. The effect of 

tax-reform on after-tax income is relatively stable until 1991 when it jumps 

from $1.2 billion to $2.3 billion due primarily to the reduction of recapture 

from $3.2 billion in 1990 to $0.5 billion in 199 I. 

Just over one-quarter of the banking system's assets in 1986 were held by 

banks with less than $500 million in assets. Comparison of the first two 

panels of Table I 0.5 indicates that $3.2 billion of the total increase of 

$6.2 billion in after-tax income flows to small banks. This larger than 

proportionate increase is not unexpected since small banks are not affected by 

recapture or repeal of the bad debt reserve method . Nevertheless. disproportionate revenue is also derived from small tlanks: collectively. small banks 

pay $2.4 billion in extra taxes while large banks only pay $3. 1 biJJion more 

than under prior Jaw over the five-year period. This is due to small banks' 

relatively large holdings of tax-exempt securities; these banks earned just 
298 Thomas S. Neubig/Martin A. Sullivan 

Table 10.5 The Effects of Tax Reform on 

Small and Large Commercial Banks, by Year, 1987-1991 

Calendar Year 1987 1988 1989 1990 1991 Total 

($ Billions) 

Banks with Less Than $500 Million in Assets 

Additional Taxable Income: 

Reserve Recapture 0.00 0.00 0.00 0.00 0.00 0.00 

Reserve Method Repeal 0.00 0.00 0.00 0.00 0.00 0.00 

Portfolio Adjustment 0.22 1.92 3.62 4.97 6.05 16.78 

Change in Tax Liability -0.08 0.14 0.46 0.80 1.11 2.43 

Change in After-Tax Income 0.16 0.50 0.75 0.86 0.90 3.16 

Banks with Greater Than $500 Million in Assets 

Additional Taxable Income: 

Reserve Recapture 3.47 1.59 2.40 3.20 0.46 10.71 

Reserve Method Repeal 0.95 0.68 0.49 -0.16 -0.51 1.44 

Portfolio Adjustment 0.24 2.08 3.92 5.39 6.55 18.19 

Change in Tax Liability -0.28 -0.19 0.90 1.49 0.80 3.10 

Change in After-Tax Income 0.36 0.50 0.41 0.31 1.39 2.97 

All Commercial Banks 

Additional Taxable Income: 

Reserve Recapture 3.47 1.59 2.40 3.20 0.46 10.71 

Reserve Method Repeal 0.95 0.68 0.49 -0.16 -0.51 1.44 

Portfolio Adjustment 0.46 4.00 7.55 10:37 12.60 34.97 

Change in Tax Liability -0.36 0.33 1.36 2.29 1.91 5.53 

Change in After-Tax Income 0.51 1.00 1.16 1.16 2.29 6.13 

under one-half of tax-exempt in teres~ income in 1984. In sum. small banks are 

bigger winners than large banks. 

D. The Effect of Tax Reform Under Alternative Scenarios 

Alternative loan loss scenarios were discussed in Section 3 and displayed 

in Table 10.2. Although it was originally expected that different loan loss 

assumptions would have a significant impact on after-tax income. model simulations under different scenarios did not confirm our suspicion. Under the 

"static" scenario. where the loan loss rate remains constant at the record 

1986 level of 0.828. net charge-offs would total $86.7 billion over the 1987-

1991 period as opposed to $52.0 billion in the model baseline extrapolation; 

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The Effect of Tax Reform on Commercial Banks 299 

therefore. by 1991 the experience reserve method tax reserve would have grown 

to $22.6 instead of $17.3. Under the worst-case "pessimistic" scenario where 

the aggregate loan loss rate rises to 0. 9 percent in 1988 and remains at that 

level through 1991, net charge-offs would total $93.3 billion over the 1987-91 

period and by 1991 the experience reserve method tax reserve would have grown 

to $22.8. However, these increases of $5.4 and $6.5 billion in taxable income 

only translate respectively into $0.5 billion and $0.6 billion in extra taxes. 

These low effective average tax rates occur because firms with large losses 

have little taxable income and pay little tax anyway. The alternative minimum 

tax has little impact since increases in loan losses reduce book income by 

almost as much as the reduction in taxable income. 

V. FUTURE EXTENSIONS OF THE BANKING MODEL 

The current version of the banking model is designed to provide revenue 

estimates and serve as a tool for analysis of the major provisions of the Tax 

Reform Act of 1986 that affect commercial banks. This section outlines 

potential model improvements for more refined estimates. 

A. Tax Provisions Not Included 

The primary reason for not modeling specific provisions is lack of data. 

The usual suggested correction for this problem is to estimate for each bank 

the missing data item from that bank's data where the relationship is determined from other information. This section lists shortcomings of the model. 

resultant biases. and potential improvements. 

1. Foreign Tax Credits 

Modeling foreign tax credits requires information about foreign taxes and 

foreign income. Alternatively, extrapolations of 1983 SOl tax return data 

could be undertaken. Non-inclusion of this provision causes U.S. taxes to be 

higher than they would be otherwise. Foreign tax credits are most advantageous to large banks with overseas income. Since tax reform reduces foreign 

tax credits. the revenue increases under tax refonn. especially for large 

banks. will be larger than shown in these simulations. The separate FTC 

limitation for income subject to gross withholding greater than 5 percent is 

estimated to yield an additional $1.1 billion in tax revenue over the 1987-91 

period. 

2. Investment Tax Credits and Accelerated Depreciation 

Estimating investment tax credits and accelerated depreciation requires 

information about tangible investment that is not available in current Call 
300 Thomas S. Neubig/Martin A. Sullivan 

Report data set. The repeal of the lTC and reduction in depreciation deductions increases the tax liabilities of all banks. and this increase in tax 

liability is not captured in these simulations. 

3. Carryforwards and Carry backs 

The model should have banks with tax losses building up stocks of unused 

NOLs and using them in years with positive taxable income. ln general, the 

non-inclusion of carryforward and carryback provisions causes tax liabilities 

to be overstated. In addition. tax liabilities of any one bank will have more 

variance over time. (Offsetting current taxable income with unused NOLs will 

smooth out peaks in tax liability.) The change in carryforward and carryback 

provisions under tax reform will cause banks to carryforward. rather than 

carryback, more losses which reduces the present value of the losses. The 

estimated revenue effect from the change was only about $0.1 billion in 

1987-91. 

4 . The "Troubled Bank" Exception 

Banks with high percentages of non performing assets are allowed to suspend 

recapture of tax reserves into income until the quality of their loan portfolio improves. Thus. these simulations recapture bad debt reserve into 

taxable income more quickly than will actually occur. This causes the 

simulation revenue estimates of tax reform to be too high in the early years 

and too low in later years. Estimates indicate that the troubled bank 

exception will reduce revenue by $0.5 billion over the 1987-9 J period. 

5. Other Excluded Provisions 

As stated earlier. these simulations allow banks with less than $500 

million in assets on an individual basis continued use of the reserve method 

(and also no recapture). This treatment overstates the extent of the small 

bank exception. Thus, the change in revenues in these simulations is understated. 

In addition, repeal of the cash method of accounting was also not modeled. 

Repeal of the cash method of accounting for banks was estimated to raise about 

$0.5 billion between 1987 and 1991. 

B. Extrapolation Features Not Included 

More elaborate extrapolation techniques would improve individual company 

estimates but have not yet been incorporated in the model . These include 

non-uniform growth rates for differen1 finns and different balance sheet and 

income statement items. and consistent treatment of balance sheet and income 

statement accounts. 

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The Effect of Tax Reform on Commercial Banks 30 1 

Even if there were a high-degree of confidence in the forecast of aggregate 

growth of bank assets and liabilities, revenue estimates are sensitive to how 

this growth is distributed among firms. More realistic revenue estimates 

would include a distribution of growth rates for individual finns consistent 

with forecasted aggregate growth. 

Growth of all assets and liabilities by the same aggregate rate. as is 

assumed in these simulations, maintains balance sheet consistency for ·each 

finn. However. banks may change the composition of their balance sheets while 

growing at the aggregate asset growth rate. The model maintains balance sheet 

consistency in the case of changes in portfolios from tax-exempt to taxable 

securities, but assumes equal growth rates for all other assets. 

If corporate profits are targeted at one growth rate and certain income or 

expense items. such as the provision for loan losses, are assumed to grow at 

different rates. assumptions about the growth rates of other income and 

expense items must be made which are consistent with each bank's income 

identity. Currently, the model does not employ a general mechanism to 

reconcile disparate growth rates of income statement items. 

Several balance sheet items. such as provision for loan losses and 

depreciation. have direct effects on the balance sheet. Conversely. income 

(or expense) flows from asset (or liability) stocks should be consistent with 

reasonable assumptions about rates of return. For example. if interestbearing assets grow by ten percent and interest rates are expected to rise, 

interest income can be expected to grow by more than ten percent. 

C. Shortcomings of Forecasts 

Aside from the issues surrounding the question of the proper extrapolation 

techniques. revenue estimates rely heavily on forecasts of target variables. 

The key target variable in these simulations is total bank assets. Bank asset 

growth is affected by macroeconomic conditions which are in themselves difficult to forecast. However, in addition. as outlined above, many non-macroeconomic factors may affect industry growth. Relaxation and/or tightening of 

various regulations of not only banks but their competitors will affect the 

future of commercial banking. Similarly. taxation of current or potential 

banking competitors or innovation in financing technology or techniques could 

affect the banking industry's share of total financial services income. 

To the extent that tax reform increases after-tax income of banks. growth 

of the banking sector should be expected. All these factors add uncertainty 

to forecasts of commercial bank assets. However. although errors in forecasts 

greatly affect the level of bank profits and taxes. the difference in aftertax profits and taxes due to tax refonn (i.e. revenue estimates) will be 

considerably smaller because the marginal tax rate is less than I 00 percent.

1 3 
302 Thomas S. Neubig/Martin A. Sullivan 

VI. SUMMARY AND CONCLUSION 

Base-broadening provisions specific to banks-namely, the repeaJ of the bad 

debt reserve method, the recapture of existing bad debt reserves into taxable 

income, and the disallowance of interest costs used to carry-tax exempts 

securities-are commonly highlighted when assessing the effects of the tax 

reform on banks. However, empirical analysis with a model using individual 

bank data shows that the added tax Hability due to these provisions, along 

with the alternative minimum tax, is offset largely by rate reduction. 

Although banks on the whole pay more taxes over the 1987-91 period, the 

banking industry's after-tax income increases because additional interest 

income wiU be earned when banks shift their portfolios to taxable securities. 

Taxable securities earn higher yields than tax-exempt securities, and, because 

of tax reform, they are taxed at lower rates. 

APPENDIX 

DERIVATION OF CONDmONS FOR 

HOLDING TAX-EXEMPT SECURmES 

Banking Facing Regular Tax 

Abstracting from the important considerations of risk and liquidity, a bank 

with only two assets picks the level of each (and implicitly, by the balance 

sheet constraint. total liabilities) in order to maximize after-tax profit. A 

finn subject only to regular tax and not the minimum tax has an after-tax 

profit function: 

P = i *TE + i *BA - i *DO - OC - • t D D 

u* {it *BA - [i *DO -b* IE* TE/(TE+ BA)] - OC} 

where P = after-tax profit; 

TE= holdings of tax-exempt securities; 

BA= holdings of other (taxable) loans and securities; 

0~ bank liabilities; 

OC= noninterest costs; 

i = interest rate on tax-exempt securities: 

• it. = interest rate on other assets: 

~ = interest rate on bank borrowing (deposits): 

u = statutory corporate tax rate: 

b = the percentage of interest expense disallowed; 

IE = total interest expense = i

0 *DO. 

(IO.Al) 

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The Effect of Tax Reform on Commercial Banks 303 

By using the balance sheet identity to eliminate BA (=DO-TE) from the 

profit function (I O.A 1 ), differentiating with respect to TE. and setting the 

derivative equal to zero. the net-after tax interest advantage of tax-exempts 

compared to taxable securities is: 

i - { 1-u)*i - u*b*r • t (l0.A2) 

where r = interest expense as a fraction of total assets ( = IE/TA). Banks 

purchase tax-exempt bonds only if (IO.A2) is positive. According to equation 

(10.A2) if taxable bonds earn 9 percent interest and bank average interests 

expense is 6 percent, under pre-tax refonn law tax-exempt bonds yielding only 

5.4 percent (or 60 percent of the comparable taxable yield) would be preferred 

to taxable investment. After-tax reform tax-exempt rates would have to rise 

to 8.0 percent (or 88.4 percent of comparable taxable yield) to be attractive 

to banks. 

Banks Facing the Alternative Minimum Tax 

A bank subject to the new alternative minimum tax has the profit function: 

P = (i. *TE + it *BA - ~ *DO - OC)*( l-0.5*m) - m*PR 

- 0.5*m * {it *BA - OC- [i0 *DD- b*IE*TE/(TE+BA)]} (IO.A3) 

where 

m = the minimum tax rate ( = 20 percent); 

PR = doUar amount of preference income. 

Again. by substituting the BA+TE for DO. differentiating with respect toTE. 

and setting the derivative of profits equal to zero, the net advantage of 

tax-exempts over taxable securities for banks subject to the minimum tax can 

be derived: 

i. * (l-0.5*m) - it *(1 -m)- 0 .5* m *b *r (JO.A4) 

For banks with taxable investments earning 9 percent, an average interest 

expense of t percent and an alternative minimum tax rate of 20 percent. the 

tax-exempt rate would have to rise above the taxable rate of 8. 7 percent for 

its after-tax yield to exceed that of taxable investment for banks. 

FOOTNOTES 

1

See Joint Committee (1984) and Marovelli (1986). 2 It should also be noted that the 1982 Tax Act reduced the benefit of PEL reserve method by 

disallowing 15 percent of the excess of the PEL method deduction over the allowable deductior 
304 Thomas S. Neubig/Manin A. Sullivan 

computed under the experience reserve method. The disallowance was increased to 20 percent for 

tax years after 1984. The disallowance affected few banks due to the phase-down of the 

allowable percentage and to the base year reserve. 3 Nonperforming loans or loans that are either 90 or more days past due. "nonaccrualloans" or 

"renegotiable troubled debt." Equity capital means the equity of a bank as defined for 

regulatory purposes. It does not include any book reserve for loan losses. 

~At the end of 1984 banks held over $170 billion in tax-eltempt investments. Banks with 

assets size of less than $300 million had tax-exempt holdings equal to 9.6 percent of their 

assets. while the larger banks held only had 6.1 percent of their assets in tax-exempt 

investments. 5

The two first stage adjustment factors and the second data adjustment factor was calculated 

as follows: 

1980 1981 1982 1983 Average 

Ratio of SOl to unadjusted model output: 

Total Receipts 1.14 l.l9 1.27 1.26 1.21 

Total Eltpenses 1.19 1.24 1.32 1.31 1.27 

Ratio of SOl to first-stage model output: 

Net Taxable Income 0.91 0.67 0.89 0.95 0.86 

6 Before--tax book profits of the banking industry as a percentage of GNP were 0.55 in 1976. 

increased to0.71 in 1979 and 1980. and declined to0.55 in 1984. Bank profits over this period 

generally moved with interest rates; however. deregulation of deposit rates will reduce the 

positive correlation between bank profit.s and interest rates. In addition, other structural 

changes in commercial banking make profits difficult to forecast. Repeal of the Glass-Steagall 

Act would allow banks to enter other activities. most notably. investment banking. which may · 

increase the banking industry's total profits in the long-run. but not necessarily in the near 

future. Income from service charges will increase banks profits. while increased competition 

from other intermediaries (e.g .. credit unions. thrifts) and financial instruments (e.g .. 

commercial paper. collateralized mortgage obligations) may reduce profits. 7 The assumption is consistent with after-tax profit maximization. if tax minimization results 

from acceleration of deductions. Banks may not want to accelerate deductions if they expect 

that tax rates they may increase or that loss carryforwards from deductions might expire. 8 As mentioned above. Call Report data is only available on an unconsolidated basis. In the 

banking model. banks eligible for the small bank eltception are defined as those individual banks 

with less than $500 million in assets. This overstates the percentage of industry assets to 

which the small bank exception applies. 9 A later paper extends the model to include endogenous financial portfolio holdings of 

commercial banks with more detailed specification of banks' tax-exempt bond holdings. See 

Neubig and Sullivan ( 1987). 1 0This differs from the standard treatment in revenue estimation of pre-enactment effects 

described in Howard Nester's "A Guide to Interpreting the Dynamic Elements of Revenue 

Estimates " in Chapter I of this volume. Consistency with the revenue estimating methodology 

would require including the end-of-1985 surge in purchases of tax-exempt securities in the 

baseline simulation. 11The estimated change in after-tax income is sensitive to the estimated future tax-exempt 

taxable yield ratio. The estimates in the paper assume taxable yields are 150 percent of 

comparable tax-exempt yields. If the yield differences narrow. then the change in after-tax 

income would be smaller. 12 In the calculation of tax revenue low average effective tax rates apply to the large amount 

of recapture in 1987 since $2 .8 billion of the total of $3.5 billion is accumulated by firms 

with no current tax liability that are assumed to have opted to accelerate recapture. 

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The Effect of Tax Refonn on Commercia] Banks 305 

13 As a simple example, consider a revision of industry five-year profits from $I 40 to $I 30 

billion. The effect of the revised forecast on the revenue estimate of a rate change (if all 

firms were fully taxable at the top rate) from 46 to 34 percent would be a revision of the 

revenue loss figure from $16.8 to $15.6 billion. 

REFERENCES 

Joint Comminee on Taxation. Study of 1983 Effective Tax Rates ofSe/uted Large Corporations, 

Joint Comminee on Taxation. November 18. 1984. 

Marovelli. F. D .. Eff~ tive Corporal~ Tax Rat~s 1980-1984, Arlington, VA: Tax Analysts. 

1986. 

Neubig, Thomas S. and Martin A. Sullivan. The Implications of Tax Reform for Bank Holdings 

of Tax-Exempt Securities. National Tax Journal. Vol. 40, No. 3. September 1987 (forthcoming).