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Financing Federal-Aid Highways

The Highway Trust Fund

The previous sections have only peripherally mentioned the Highway Trust Fund (HTF). This has been intentional. The fact that the HTF is the source of funds for the Federal-Aid Highway Program (FAHP) has a limited impact on the financial procedures under which the highway program operates. The use of the Trust Fund provides two direct benefits to the highway program: (1) It allows the program to operate with contract authority through the 1974 Budget Act, and (2) it provides the opportunity for revenue aligned budget authority (see discussion under "Appropriations"). The following section briefly describes the operation of the HTF.


Before 1956, the year Interstate System authorizations were greatly increased, the HTF did not exist. Cash to liquidate previously incurred obligations for the FAHP came from the General Fund of the Treasury. Budget authority came through the granting of contract authority, as it does now. Although taxes on motor fuels and automobile products were in existence, they were not linked to funding for highways. At the time, financing for the highway program and revenues from automobile and related products were included under the public finance principle of "spend where you must, and get the money where you can." Aside from this, the program operated in terms of authorizations, obligations, appropriations, and reimbursements—much as it does now.

The Federal-Aid Highway Act of 1956, coupled with the Highway Revenue Act of that same year, increased authorizations for the Federal-aid Primary and Secondary Systems, authorized significant funding of the Interstate System, and established the HTF as a mechanism for financing the accelerated highway program.67 To finance the increased authorizations, the Revenue Act increased some of the existing user taxes, established new ones, and provided that most of the revenues from these taxes should be credited to the HTF. Revenues accruing to the HTF were dedicated to the financing of Federal-aid highways. The passage of the Highway Revenue Act of 1956 also increased the political acceptability of the additions in the user taxes and provided earmarked revenues to finance the larger highway program.

The imposition of the taxes that are dedicated to the HTF, as well as the authority to place the taxes in the HTF and to expend from the HTF all have expiration dates which must be extended periodically. The 1956 Highway Revenue Act provided for the imposition of the taxes that support the HTF through June 30, 1972, and the transfer of such taxes and the payment of refunds through June 30, 1973. Expenditures from the HTF were authorizedthrough June 30, 1972. The life of the HTF has been extended several times by subsequent legislation, most recently by the TEA-21, which extended the imposition of taxes through September 30, 2005,68 and the transfer of the taxes to the HTF and the payment of refunds through June 30, 2006. The TEA-21 authorized expenditures from the HTF through September 30, 2003.

User Taxes

The HTF was created as a user-supported fund. Simply, the revenues of the HTF were intended for financing highways, with the taxes dedicated to the HTF paid by the users of highways. This principle is still in effect, but the tax structure has changed since 1956. Major revisions occurred as a result of the Surface Transportation Assistance Act (STAA) of 1982 and the Deficit Reduction Act of 1984. Those acts increased the motor-fuel taxes for the first time since 1959. The 1982 STAA also established a special Mass Transit Account in the HTF to receive part of the motor-fuel tax.69

Then, another increase of 5 cents per gallon (bringing the Federal gasoline tax to 14.1 cents per gallon) was enacted as part of the Omnibus Budget Reconciliation Act of 1990 (OBRA 90). That increase was effective December 1, 1990. The act also established a "first" for the HTF. One-half of the revenues derived from the 5-cent increase went to the General Fund of the Treasury for deficit reduction. Previously, virtually all revenues from Federal motor-fuel (and other highway-related Federal excise taxes) had been credited entirely to the HTF.70 The General Fund portion of the tax was imposed on a temporary basis and was scheduled to expire on October 1, 1995.

Another fuel tax increase of 4.3 cents per gallon was enacted effective October 1, 1993, by the Omnibus Budget Reconciliation Act of 1993. The increase brought the gasoline tax to 18.4 cents per gallon and the entire amount of the increase was directed to the General Fund of the Treasury for deficit reduction. This tax increment has no expiration date. The legislation also provided that the temporary General Fund fuel tax imposed by OBRA 90 would be extended and that it would be directed to the HTF effective October 1, 1995, except in the case of certain alcohol fuels.71

The Taxpayer Relief Act of 1997 redirected the 4.3-cents General Fund tax to the HTF effective October 1, 1997. The TEA-21 extended the HTF taxes through September 30, 2005, thus extending the fiscal "life" of the HTF.

Table 4 shows the types of taxes placed in the HTF and the rates currently in effect. Appendix M shows the history of the highway fuel tax rates since the creation of the HTF.

Table 4.—User Fee Structure.
Tax Type   Tax Rate
Gasoline 18.4 cents per gallon
Diesel 24.4 cents per gallon
Gasohol (10% ethanol) * 13 cents per gallon
Special Fuels:

General rate 18.4 cents per gallon

Liquefied petroleum gas 13.6 cents per gallon

Liquefied natural gas 11.9 cents per gallon

M85 (from natural gas) 9.25 cents per gallon

Compressed natural gas 48.54 cents per thousand cubic feet

0-40 pounds No Tax

Over 40 pounds to 70 pounds 15¢ per pound in excess of 40

Over 70 pounds to 90 pounds $4.50 plus 30¢ per pound in excess of 70

Over 90 pounds $10.50 plus 50¢ per pound in excess of 90
Truck and Trailer Sales 12 percent of retailer's sales price for tractors and trucks over 33,000 pounds gross vehicle weight (GVW) and trailers over 26,000 pounds GVW
Heavy Vehicle Use Annual tax: Trucks 55,000 pounds and over GVW, $100 plus $22 for each 1,000 pounds (or fraction thereof) in excess of 55,000 pounds (maximum tax of $550)

* Other rates apply to gasohol blends containing less than 10 percent ethanol or blends made with methanol.

The HTF has an additional source of revenue. Since October 30, 1984, the proceeds from fines and penalties imposed for violation of motor carrier safety requirements are deposited in the Highway Account of the HTF.72


Most of the excise taxes credited to the HTF are not collected by the Federal government directly from the consumer. They are, instead, paid to the Internal Revenue Service by the producer or importer of the taxable product (except in the cases of the tax on trucks and trailers, which is paid by the retailer, and the heavy vehicle use tax, which is paid by the heavy vehicle owner). As a result, most of the Federal fuel taxes come from a handful of States, those where major oil companies are headquartered, and most tire taxes are paid from Ohio, the home of the U.S. tire industry. Of course, these taxes become part of the price of the product and are ultimately paid by the highway user.

User taxes are deposited in the General Fund of the Treasury and the amounts equivalent to these taxes are then transferred on paper to the HTF. Transfers are made at least monthly on the basis of estimates by the Secretary of the Treasury and later adjusted on the basis of actual tax receipts.73 Amounts in the HTF in excess of current expenditure requirements are invested in public debt securities. Until October 1, 1998, the securities were interest-bearing and interest from the securities was credited to the fund. Since that time, the HTF balance has been invested in non-interest-bearing securities.74

Since there is considerable interest in the amount of contributions to the HTF made by each State, estimates are made of the amount of taxes paid by the highway users of each State on the basis of data reported by State motor-fuel tax agencies. Highway users in some States pay more in user taxes than those States receive back in Federal-aid highway apportionments andallocations. In an effort to compensate for this, the TEA-21 included a provision, called the Minimum Guarantee, that distributes additional funds to the States. This provision is described in detail in the "Financing Procedures" section of this book.

Pay-as-You-Go Fund

Another important characteristic of the HTF is that it was set up as a pay-as-you-go fund. In other words, there must be enough money in the HTF to make reimbursements. For the Highway Account of the HTF, the control mechanism that ensures this is the Byrd Amendment.75

Under the Byrd Amendment, as modified by the STAA of 1982, unfunded authorizations (unpaid commitments in excess of amounts available in the Highway Account of the HTF) at the end of the fiscal year in which the apportionment is to be made must be less than the revenues anticipated to be earned in the following 24 month period. For example, to determine the status of FY 1999, at the close of FY 1998 the Secretary of the Treasury must determine if the balance of the Highway Account of the HTF as of September 30, 1998, plus the anticipated income in FYs 1999, 2000, and 2001, will be greater than the sum of the authorizations to be distributed for FY 1999 and the authorizations distributed, but not paid, as of September 30, 1998. If there will be a shortfall in funds, then all Highway Account funded program apportionments for FY 1999 will be reduced proportionately.76

In the HTF’s history, the Byrd Amendment has been triggered only once, resulting in the reduction in the Interstate System construction apportionments for FY 1961. No Byrd Amendment reductions are anticipated for the foreseeable future. The Mass Transit Account was subject to a similar test, known as the Rostenkowki test; the only difference was that the Rostenkowski test measured outstanding commitments against estimated income for 1 year instead of 2. With the enactment of the TEA-21, the Mass Transit Account is subject to the same 2-year test as the Highway Account. The tests are applied to each account separately.

Balance of the Highway Trust Fund

The balance of the HTF has long been a point of controversy. Because of the nature of a reimbursable program like the FAHP, there will always be cash in the fund that is not needed for immediate use. It is important to understand that this is not necessarily excess cash but will be needed to reimburse the States as vouchers are submitted.

Perhaps a comparison of the HTF operation to a personal financial situation can help clarify this point. If a person has a checking account balance of $500, that amount cannot be considered excess if he or she has at the same time outstanding monthly bills of $1,000, but neither is the account in a deficit situation if he or she will receive $1,200 in a paycheck at the end of the month.

The HTF operates in the same manner. Although there was a cash balance of $16.5 billion in the Highway Account of the HTF at the close of FY 1998 (see Table 5), there were also, at the same time, unpaid commitments (authorizations already apportioned/allocated to the States) against the HTF totaling almost $50 billion. Therefore, the $16.5 billion balance was not excess cash.

Table 5.—Operation of the Highway Account of the Highway Trust Fund (Amounts in Millions of Dollars).
Mass Transit
Opening balance, 10/01/97 12,576 9,858 22,433
Tax receipts 23,969 3,658 27,627


Transfers to other trust funds

172 23 195

Tax refunds

656 148 804

Net tax receipts

23,141 3,487 26,628
Interest 1,166 839 2,005
Expenditures 20,347 4,133 24,480
Closing balance, 9/30/98 16,536 10,051 26,586

If the highway revenues were to have stopped completely at the close of FY 1997, the debts (unpaid authorizations) would have exceeded the cash on hand by about $31 billion. Since the highway program functions as areimbursable program, with cash outlays following obligations at a later date, this situation is quite proper.

The difference between commitments and income through the termination of the fund is the amount that truly reflects the status of the fund and must be considered when any new commitments (additional authorizations) are proposed. It also must be recognized that this status is based on revenue projections that can change from time to time. The projected commitments can also change, either by legislation authorizing additional funds or when programs, such as the Minimum Guarantee, exceed estimated authorizations.

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Electronic version of Publication No. FHWA-PL-99-015

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