Most of DOT's budget isn't discretionary at all. It's trust-fund contract authority under an obligation limit.
Office of the Chief Financial Officer · U.S. Department of Transportation
DOT does not fit a plain discretionary-budget frame. Of the FY2027 request's $114.1B in total budgetary resources, only $26.8B is gross discretionary budget authority. The rest is overwhelmingly Highway Trust Fund contract authority controlled by annual obligation limitations — money the budget document classes as mandatory, not ordinary discretionary BA. This monitor leads with that structure and never sums obligation limitations and discretionary BA into one number.
FY2027 total budgetary resources
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all funds — discretionary + mandatory
FY2027 mandatory subtotal
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mostly trust-fund oblim — NOT discretionary BA
Mandatory ÷ discretionary
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By administration — base “Total”, FY2027 request
$ in thousands · IIJA/disaster supplementals excludedFHWA is the largest administration and the clearest case of the structure: Federal-Aid Highways is contract authority from the Highway Trust Fund under an obligation limitation, classed mandatory. The account-by-account breakdown, with each administration's rows summing to its published base Total, is on the appropriations view.