OTHER INFORMATION (UNAUDITED) 208

Tax Expenditures

As discussed in greater detail in Note 17—Collections and Refunds of Federal Revenue, tax and other revenues 

reported reflect the effects of tax expenditures, which are special exclusions, exemptions, or deductions or which provide tax 

credits, preferential tax rates or deferrals of tax liability, that allow individuals and businesses to reduce taxes they may 

otherwise owe. 

The figures reported in the following table are estimates of tax expenditures using data from previous years and 

economic forecast from the fiscal year 2018 Midsession Review. The largest tax expenditures in fiscal year 2018 are the 

following (and see the table below):

x The exclusion from workers’ taxable income of employers’ contributions for health care, health insurance 

premiums, and premiums for long-term care insurance; 

x The exclusion of contributions to and the earnings of employer defined benefit and defined contribution pension 

funds (minus pension benefits that are included in taxable income); 

x Preferential tax rates on long-term capital gains; 

x Imputed rental income forms part of the total value of goods and services produced in a country. But unlike returns 

from other investments, the return on homeownership “imputed rent” is excluded from taxable income. In contrast, 

landlords must count as income the rent they receive, and renters may not deduct the rent they pay. A homeowner is 

effectively both landlord and renter, but the tax code treats homeowners the same as renters while ignoring their 

simultaneous role as their own landlords and exempting potential rent they would have paid themselves; and 

x Accelerated depreciation of machinery and equipment.

Largest Income Tax Expenditures

(In billions of dollars) 2018

Exclusion of employer contributions for medical insurance premiums & health care.................. 205.1

Defined benefit & defined contribution pension funds ............................................................. 142.2

Preferential tax rates on long-term capital gains..................................................................... 118.6

Exclusion of net imputed rental income ................................................................................. 116.6

Accelerated depreciation of machinery and equipment........................................................... 67.8

Generally, identifying and measuring a tax expenditure requires defining a baseline tax system against which identified 

tax provisions are exceptions. The tax expenditures prepared for the Budget are estimated relative to a simplified 

comprehensive income tax, which defines income as the sum of consumption and the change in net wealth in a given period 

of time. Tax expenditure estimates do not necessarily equal the increase in federal revenues (or the change in the budget 

balance) that would result from repealing these special provisions, for the following reasons: 

x Eliminating a tax expenditure may have incentive effects that alter economic behavior, which can affect the resulting 

magnitudes of the activity or of other tax provisions or government programs. For example, if capital gains were 

taxed at ordinary rates, capital gain realizations would be expected to decline, resulting in lower tax receipts. Such 

behavioral effects are not reflected in the estimates. 

x Tax expenditures are interdependent even without incentive effects. Repeal of a tax expenditure provision can 

increase or decrease the tax revenue effect of other provisions. For example, even if behavior does not change, 

repeal of an itemized deduction could increase revenue costs from other deductions as some taxpayers move into 

higher tax brackets. Alternatively, an itemized deduction repeal could lower the revenue foregone from other 

deductions if taxpayers choose to claim the standard deduction over itemizing. Similarly, if two provisions were 

repealed simultaneously, the tax liability increase could be greater or less than the sum of the two separate tax 

expenditures, because each is estimated assuming that the other remains in force. 

x Repeal effects may depend on concurrent tax rate changes. Lowering or raising tax rates can decrease or increase the 

estimated revenues from a particular provision. A $10,000 charitable contributions deduction is worth $3,500 in 

corporate tax revenues at a 35 percent tax rate, but only $2,100 at a 21 percent tax rate. 
209 OTHER INFORMATION (UNAUDITED)

The President’s fiscal year 2006 Budget provided a presentation of the Department of the Treasury’s review of the tax 

expenditure budget. It focused on potential alternative baselines to a comprehensive income tax, including using a 

consumption tax, and defining negative tax expenditures (provisions that cause taxpayers to pay too much tax). Relative to a 

consumption tax baseline, a number of current tax provisions would be negative tax expenditures. More specifically, a 

consumption tax will not extend to saving or capital income. As an example, the exclusion for contributions to and earnings 

from retirement accounts would not be treated as a tax expenditure. Some of these also may not necessarily be negative tax 

expenditures under a comprehensive income tax as a baseline; the current reference law and normal law baselines represent a 

simplified version of comprehensive income. As an example, some medical expenditures may not be discretionary and 

perhaps should be excluded from income. 

A more comprehensive ranking, including rankings over a 10 year period, and descriptions of tax expenditures can be 

found at the following location from the Treasury’s Office of Tax Policy https://home.treasury.gov/policy-issues/taxpolicy/tax-expenditures.