The federal gas tax is 18.4 cents per gallon of gasoline. For diesel, the federal tax is 24.4 cents per gallon. That amount is charged by the gallon, not by the dollar price on the pump. So when gas prices move up or down, the federal tax per gallon stays the same. The IRS lists gasoline at $0.184 per gallon and diesel fuel and kerosene at $0.244 per gallon.
For a normal 12-gallon gasoline fill-up, the federal gas tax comes to about $2.21. For 15 gallons, it comes to $2.76. That is only the federal part. Your receipt may also reflect state taxes and other charges, depending on where you buy fuel.
Why Diesel Has a Higher Federal Tax
Diesel carries a higher federal tax because it is tied closely to heavy road use. Trucks, buses, delivery fleets, farm transport, and many work vehicles use diesel. These vehicles often place more wear on roads and bridges than smaller passenger cars.
The federal diesel tax is 24.4 cents per gallon. Gasoline is 18.4 cents per gallon. Both figures include a small 0.1-cent-per-gallon fee for the Leaking Underground Storage Tank program, often called the LUST fee in official fuel tax material. The EIA says federal taxes include 18.3 cents on gasoline and 24.3 cents on diesel, plus the 0.1-cent fee on both fuels.
Where the Money Goes
The federal gas tax helps fund the Highway Trust Fund. This fund supports road work, bridge work, and other transportation needs. The Federal Highway Administration says motor fuel taxes on gasoline and diesel make up a large share of money deposited into the Highway Trust Fund. It also says all but 0.1 cent per gallon goes to that fund.
The money does not simply sit at the gas station. The FHWA says the revenue is placed into the Highway Trust Fund by the U.S. Treasury after collection by the IRS. The funds are then sent to states through formulas set in federal law.
Has the Federal Gas Tax Changed Recently?
No official current source I checked shows a new federal gas tax rate. The FHWA states that the gasoline and diesel motor fuel tax rates have stayed unchanged since 1993.
That long freeze matters. Since the tax is a fixed cents-per-gallon charge, it does not rise automatically when construction costs, labor costs, or fuel prices rise. A gallon bought today still carries the same federal gasoline tax rate set decades ago.
Federal Tax Is Not the Whole Pump Tax
The federal gas tax is only one part of what drivers pay in taxes on fuel. States can add their own gasoline and diesel taxes and fees. Those state costs vary a lot. The EIA says state taxes do not include county and local taxes, and state-level fuel tax rules can include excise taxes, environmental taxes, inspection fees, and other charges.
That is why two drivers can pay the same federal gas tax but see different total tax costs in different states. The federal rate is the same across the country. The state and local side can change the final number.
The Bottom Line
The federal gas tax is easy to pin down: 18.4 cents per gallon for gasoline and 24.4 cents per gallon for diesel. It is charged by the gallon, it does not change with the retail price of fuel, and it helps support federal transportation funding.
So when you fill up, the federal share is only one piece of the final pump price. The larger picture includes crude oil costs, refining, distribution, retail costs, state taxes, and local charges. But the federal gas tax itself remains a fixed amount per gallon.
