The Highway Revenue Act of 1956 established the Highway Trust Fund as an accounting mechanism to help finance federal highway programs. In 1983, the Highway Trust Fund was divided into two accounts: a Highway Account and a Mass Transit Account. Receipts to the Highway Account are used to fund highway programs, through which billions of dollars are distributed to the states annually for the construction and repair of highways and related activities. Treasury uses a revenue allocation and reporting process to distribute highway user taxes to the Highway Trust Fund. Financing for the Highway Trust Fund is derived from a variety of federal highway user taxes including excise taxes on motor fuels (gasoline, gasohol, diesel, and special fuels) and tires, sales of new trucks and trailers, and the use of heavy vehicles. As table 1 shows, the excise tax rates and distribution of the tax revenues vary. The different tax rates reflect federal policy decisions. For example, in the 1970s and 1980s, the federal government adopted numerous policies to encourage the use of alternatives to imported fossil fuels and help support farm incomes. Among these policies were tax incentives that targeted the use of alcohol fuels derived from biomass materials, such as ethanol. Ethanol blended fuels (gasohol) are partially exempt from the standard excise tax on gasoline (18.4 cents). The proportion of ethanol contained in each gallon of fuel determines the size of the partial exemption. The most common ethanol blend contains 90 percent gasoline and 10 percent ethanol and is currently taxed at 13.1 cents per gallon—an exemption of 5.3 cents. The federal government also uses the distribution of excise tax receipts to different accounts to achieve policy goals. For example, a small part of the excise tax on most motor fuels is distributed to the Leaking Underground Storage Tank Trust Fund to clean-up contamination caused by underground storage tanks. Additionally, 2.5 cents of the tax received on each gallon of gasohol is transferred to the General Fund, rather than the Highway Trust Fund, for deficit reduction purposes. TEA-21 continued the use of the Highway Trust Fund as the mechanism for accounting for federal highway user taxes. TEA-21 also established guaranteed spending levels for certain highway and transit programs. Prior to TEA-21, these programs competed for budgetary resources through the annual appropriations process with other domestic discretionary programs. New budget categories were established for highway and transit spending, effectively establishing a budgetary “firewall” between those programs and other domestic discretionary spending programs. Of the $217.9 billion authorized for surface transportation programs over the 6-year life of TEA-21, about $198 billion is protected by the budgetary firewall—about $162 billion for highway programs and $36 billion for transit programs. Under TEA-21, the amount of highway program funds distributed to the states is tied to the amount of actual tax receipts credited to the Highway Account of the Highway Trust Fund. TEA-21 guaranteed specific levels of funding for highway programs from fiscal year 1999 through fiscal year 2003, on the basis of projected receipts of the Highway Account. TEA-21 also provided that beginning in fiscal year 2000, this guaranteed funding level for each fiscal year would be adjusted upward or downward through the RABA calculation as the levels of Highway Account receipts increased or decreased. To determine the RABA adjustment, the Office of Management and Budget and the Office of the Secretary in the Department of Transportation rely on information on Highway Account receipts and revised Highway Account projections supplied by Treasury. Specifically, the Bureau of Public Debt provides the actual Highway Account receipts for the prior fiscal year, and the Office of Tax Analysis (OTA) provides a projection of Highway Account receipts for the next fiscal year. On the basis of the information we reviewed, the fiscal year 2003 RABA calculation—a negative $4.369 billion—appears reasonable. The RABA adjustment for fiscal year 2003 was calculated by (1) comparing the actual Highway Account receipts for fiscal year 2001 to the projections of receipts for fiscal year 2001 included in TEA-21, and an adjustment for the RABA calculation made for that year (the look back portion of the calculation) and (2) comparing projections of Highway Account receipts for fiscal year 2003 with the projection of these receipts contained in TEA-21 (the look ahead portion of the calculation). The sum of these differences is the RABA adjustment. Table 2 shows the RABA calculations for fiscal years 2000 through 2003. As shown, the RABA adjustments for fiscal year 2000 through fiscal year 2002 were positive—increasing highway funding levels by a total of over $9 billion. However, the RABA adjustment for fiscal year 2003 is negative $4.369 billion. Eighty percent of the fiscal year 2003 RABA adjustment is attributable to the look back portion of the calculation. The actual fiscal year 2001 Highway Account receipts were about $1.6 billion lower than projections in TEA-21. According to Treasury, actual fiscal year 2001 receipts were lower than expected due to the slowdown in the economy, which especially affected heavy truck sales, and increased gasohol use. We reviewed the amounts distributed to the Highway Trust Fund for the first 9 months of fiscal year 2001, and concluded that these amounts were reasonable and adequately supported on the basis of available information. With respect to the look ahead portion of the calculation, we reviewed Treasury’s process for projecting Highway Account revenues. Although we did not independently evaluate the methodology and the economic models Treasury used to develop its revenue projections, our review of a qualitative description of the process, key inputs, and changes to the models gave us no reason to question the resulting projections. The Secretary of the Treasury transfers applicable excise tax receipts, including receipts from gasoline and other highway taxes, from the General Fund to the excise tax related trust funds, including the Highway Trust Fund, on a monthly basis. These transfers are based on estimates because actual data on which to base the allocations are not available when the deposits are initially made. OTA prepares these estimates on the basis of historical IRS certification data and actual excise tax revenue collections. Subsequently, IRS certifies the actual excise tax revenue collections that should have been distributed to the trust funds on the basis of tax returns and payment data. Using the IRS certifications, Treasury makes quarterly adjustments to the initial trust fund distributions. For example, in March 2001, Treasury made an adjustment to decrease the fiscal year 2001 excise tax revenue distributions to the Highway Trust Fund to correct for actual collections in the fourth quarter of fiscal year 2000. The certified fourth quarter receipts were $1.2 billion less than the amount initially distributed on the basis of OTA’s estimates for that quarter. According to an OTA official, OTA had calculated the original estimated transfer amounts for the quarter using an economic model that assumed a higher rate of economic growth through calendar year 2000 than was actually the case. As a result, the downward adjustment was made, reducing the fiscal year 2001 distributions to the Highway Trust Fund by $1.2 billion, which contributed to the fiscal year 2003 negative RABA adjustment. Our past reports have identified errors and problems with Treasury’s excise tax allocation process. However, Treasury has made and continues to make improvements to this process. On February 11, 2002, we issued a report on the results of procedures we performed related to the distributions of excise tax revenue to the Highway Trust Fund in fiscal year 2001. On the basis of this work, we believe the amounts distributed to the Highway Trust Fund for the first 9 months of fiscal year 2001, which were subject to IRS’ quarterly excise tax certification process and which were adjusted on the basis of this process, were reasonable and were adequately supported according to available information. Additionally, we believe the March 2001 adjustment made by Treasury to reduce fiscal year 2001 excise tax distributions to the Highway Trust Fund by $1.2 billion was reasonable and adequately supported. IRS expects to deliver the results of its certifications for distributions of excise tax revenue collected during the period July 1, 2001, through September 30, 2001 to Treasury’s Financial Management Service by March 20, 2002. Consequently, the distributions of fourth quarter fiscal year 2001 excise tax revenue were based solely on estimates prepared by OTA. We did not draw any conclusions about the reasonableness of the distributions made to the Highway Trust Fund for the fourth quarter of fiscal year 2001. One component of the look back portion of the RABA calculation is the comparison of actual fiscal year 2001 Highway Account receipts with projections of those receipts in TEA-21. The actual receipts were about $1.6 billion lower than the amounts contained in TEA-21. According to Treasury, the lower than expected highway excise tax receipts in fiscal year 2001 were due to several factors. Most importantly, the weakened economy contributed to a decline in highway excise taxes paid. All but one of the Highway Trust Fund receipt sources were lower in fiscal year 2001 than 2000. For example, tax revenue from the retail tax on trucks dropped 55 percent from fiscal year 2000 to fiscal year 2001. It is important to note that the tax is applied to the sale of new trucks only. As the economy weakened, large numbers of used trucks were placed on the market, which depressed prices and sales in the new heavy truck market. In addition to the economic downturn, the rise in the use of gasohol contributed to decreased Highway Account receipts. The amount of gasohol receipts allocated to the Highway Account rose by 17.5 percent between fiscal years 2000 and 2001, which Treasury believes is evidence of an ongoing substitution of gasohol fuels for gasoline. Because gasohol is taxed at a lower rate than gasoline and a portion of the tax on gasohol is transferred to the General Fund, increases in gasohol use and corresponding reductions in gasoline use decrease Highway Account revenues. While not the main factor, the look ahead portion of the RABA calculation also contributed to the overall negative RABA adjustment.