Fast Facts

The Airport and Airway and the Highway Trust Funds are the main funding sources for federal aviation and ground transportation programs. User taxes on airline tickets, aviation fuel, tires, or gasoline are their primary source of funding. The IRS is responsible for collecting those taxes and certifying the amounts distributed to the trust funds.

We performed audit procedures requested by the Department of Transportation Office of Inspector General related to the tax revenue IRS collected and certified to the trust funds to assist the OIG in auditing DOT’s financial statements. We make no overall conclusion on the results of those procedures.

Pen and tax form

Pen and tax form

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What GAO Found

Why GAO Did This Study

GAO performed agreed-upon procedures solely to assist the DOT OIG in ascertaining whether the net excise tax revenue distributed to the AATF and the HTF for the fiscal year ended September 30, 2019, is supported by underlying records. The DOT OIG is responsible for the sufficiency of these agreed-upon procedures to meet its objectives, and GAO makes no representation in that respect. The procedures GAO agreed to perform were related to (1) transactions that represent the underlying basis of amounts distributed from the General Fund to the AATF and the HTF during fiscal year 2019, (2) IRS's quarterly AATF and HTF excise tax receipt certifications prepared during fiscal year 2019, (3) OTA's estimates of excise tax amounts to be distributed to the AATF and the HTF for the fourth quarter of fiscal year 2019, and (4) the amount of net excise taxes to be distributed to the AATF and the HTF for fiscal year 2019.

For more information, contact Cheryl E. Clark at (202) 512-3406 or

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