It’s that time of year, when dueling budget baselines means two sets of estimates for the future cash flow of the transportation trust funds.

Highways. The Administration and Congressional estimating bodies are in general agreement. Both the White House Office of Management and Budget and the Congressional Budget Office forecasts for Highway Trust Fund receipts and spending through the year 2029 are within 1 percent of so of each other each year. (The CBO forecast goes through 2034; the public OMB forecast only goes through 2029).

Both forecasts agree that the Trust Fund will remain solvent until mid-2028. OMB projects the Trust Fund will end FY 2027 with a unified balance of $28.3 billion and will run out mid-2028; CBO has its end-of-2027 balance $3.2 billion lower and its default date a month or two sooner.

Aviation. It’s harder to compare the two sets of estimates for the Airport and Airway Trust Fund. The OMB forecast and CBO forecast have different presentation stemming from the COVID period when Congress started comingling general fund airport grants with Trust Fund airport grants. CBO removes those general fund appropriations from its presentations of Trust Fund cash flow, but OMB does not. So, for the already-completed FY 2023, CBO says the fiscal year started with a balance of $16.9 billion and ended with a balance of $19.3 billion, while OMB says that the Trust Fund started the year with a balance of $12.7 billion and ended it with a balance of $18.2 billion.

Looking forward, the CBO present law baseline projects that the Trust Fund’s end-of-year cash balance will rise from $19.3 billion to an astounding $64.9 billion at the end of the decade (Sept. 2034). CBO also shows an estimate for the “uncommitted” balance (dollars that have not been obligated and are not waiting to be spent on a specific, already-made commitment), which would go from the current $8.5 billion up to $55.8 billion.

This allows plenty of room for new spending out of the Trust Fund without damaging its solvency, so the Administration has proposed a new 5-year FAA capital program from the Trust Fund that would increase outlays by $7.6 billion over the decade. (The Administration is also proposing a tax increase on jet fuel used by non-airline jets that would recoup $2.5 billion in additional Trust Fund taxes over a decade, so the net effect would be a $5.1 billion decrease in balances by 2034.)

As mentioned above, the OMB forecasts only go through 2034, but even with the additional spending for the new capital program, the President’s forecast shows year-end cash balances increasing from $18.2 billion at the end of 2023 to $28.4 billion at the end of 2029.