The federal diesel fuel tax is 24.4 cents per gallon on clear diesel used on public roads. That figure is made up of a 24.3-cent base excise tax and a 0.1-cent surcharge that funds cleanup of leaking underground storage tanks.1Office of the Law Revision Counsel. 26 USC 4081 – Imposition of Tax Off-road diesel dyed red is treated differently and generally carries no federal excise tax at all.
How the Tax Gets to the Pump
You never write a check for the diesel tax directly. It is collected when fuel leaves a refinery or terminal, paid first by refiners and terminal operators, then passed downstream through distributors and retailers until it sits inside the price posted at the pump.1Office of the Law Revision Counsel. 26 USC 4081 – Imposition of Tax Collecting high in the supply chain is what makes the tax hard to evade.
Congress set the current rate in 1993. It has not changed since. Proposals to raise or index the number have gone nowhere, so 24.4 cents per gallon is the rate heading into 2026.
Where the Money Goes
Nearly all of it funds the Highway Trust Fund. Of the 24.4 cents, about 21.44 cents goes to the Highway Account for road and bridge work, and 2.86 cents goes to the Mass Transit Account for public transit.2Office of the Law Revision Counsel. 26 USC 9503 – Highway Trust Fund The last 0.1 cent goes to the Leaking Underground Storage Tank Trust Fund for environmental remediation at contaminated fuel sites.
Dyed Diesel and the Off-Road Exemption
Diesel destined for off-road use — farm equipment, construction machinery, stationary generators — is exempt from the 24.3-cent federal excise tax when it is dyed red before leaving the terminal.3Office of the Law Revision Counsel. 26 USC 4082 – Exemptions for Diesel Fuel and Kerosene The red dye is a visible flag that the fuel was never taxed for highway use. Putting dyed diesel in any vehicle driven on public roads is not legal.
Getting caught with dyed diesel in a highway vehicle costs the greater of $1,000 or $10 for every gallon in the tank.4Office of the Law Revision Counsel. 26 USC 6715 – Dyed Fuel Sold for Use or Used in Taxable Use For repeat offenders, the $1,000 floor multiplies by the number of prior violations, so a third offense starts at $3,000 before the per-gallon calculation begins. Federal and state inspectors run random tank checks on commercial vehicles, and the dye remains chemically detectable even after the tank has been topped off with clear fuel.
If you store dyed diesel on your property, label the tank clearly and keep those purchase records separate from any clear diesel receipts. Accidental mixing is much easier to prevent than to explain later.
Who Can Get the Tax Refunded
Sometimes clear, fully taxed diesel ends up powering something that would have qualified for the exemption. When that happens, several categories of users can recover most or all of the federal tax through credits or refunds. The IRS instructions for Form 4136 list the qualifying nontaxable uses:5Internal Revenue Service. Instructions for Form 4136 and Schedule A Credit for Federal Tax Paid on Fuels
- Diesel used on a farm for farming purposes, not for hauling crops on a public highway
- Off-highway business use, meaning diesel that powers equipment not registered as a highway vehicle
- Diesel purchased for exclusive state or local government use, with the credit typically claimed by the registered vendor
- Diesel consumed by school buses transporting students
- Diesel purchased for exclusive use by nonprofit educational organizations
- Intercity and local transit buses, which pay a reduced effective rate
Railroads sit in their own category. Diesel used in trains qualifies for refund of nearly the entire excise tax, everything except the 0.1-cent Leaking Underground Storage Tank surcharge.6Office of the Law Revision Counsel. 26 USC 6427 – Fuels Not Used for Taxable Purposes Railroads pay the full 24.4 cents at purchase but effectively bear just a fraction of a cent per gallon after claiming the credit.
How to File for a Refund
The IRS provides two paths, and which one fits depends on how quickly you need the money back.
- Form 4136 attaches to your annual income tax return and applies the fuel tax credit against your overall tax liability. This is the simplest route for most filers.5Internal Revenue Service. Instructions for Form 4136 and Schedule A Credit for Federal Tax Paid on Fuels
- Form 8849 is a standalone refund claim you can file during the year without waiting for tax season. Businesses with substantial fuel expenses often prefer it because it accelerates cash flow.7Internal Revenue Service. About Form 8849, Claim for Refund of Excise Taxes
One threshold catches people off guard. Quarterly claims on Form 8849, Schedule 1 must total at least $750.8Internal Revenue Service. Schedule 1 (Form 8849) – Nontaxable Use of Fuels If your claim falls short, you can aggregate across quarters until you hit $750, or skip quarterly filing and claim the full credit annually on Form 4136.
Records You Need
Gather these before you start either form:
- Purchase invoices showing date, vendor, and gallons bought
- Equipment logs identifying which machines burned the fuel
- A clear separation between propulsion fuel and fuel used by auxiliary systems, such as a refrigeration unit with its own dedicated tank, which may qualify for a credit even on a highway vehicle
- Your Employer Identification Number or Social Security Number
Form 4136 requires you to categorize fuel by its specific nontaxable use — farming, off-highway business, export, government operations, and so on. Each category can carry a different credit rate per gallon, so accurate gallon counts directly affect how much you recover. Keep supporting documents for at least three years after filing the return that includes the credit.5Internal Revenue Service. Instructions for Form 4136 and Schedule A Credit for Federal Tax Paid on Fuels
Processing Times and the Deadline
E-filed Form 8849 claims using Schedules 2, 3, or 8 are generally processed within 20 days of IRS acceptance. Claims filed with other schedules take roughly 45 days.9Internal Revenue Service. Frequently Asked Questions – Form 8849, Claim for Refund of Excise Taxes Paper filings run longer.
The window to claim runs three years from the date your return was filed, or two years from the date the tax was paid, whichever is later.10Office of the Law Revision Counsel. 26 USC 6511 – Limitations on Credit or Refund Miss it and the credit disappears no matter how clean your records are.
State Taxes Sit on Top of the Federal Rate
The 24.4 cents is only the federal piece. Every state layers its own excise tax on top, and rates range from roughly 9 cents per gallon at the low end to over 74 cents per gallon at the high end. Some states also impose sales taxes, gross receipts surcharges, or environmental fees on diesel. A carrier filling up in one state can pay 30 or 40 cents more per gallon than in the state next door.
For commercial trucks that cross state lines, the International Fuel Tax Agreement collapses the paperwork into one quarterly return filed with the carrier’s home jurisdiction, which then redistributes revenue to other states based on miles actually driven in each. IFTA applies to vehicles with two axles and a gross vehicle weight over 26,000 pounds, three or more axles at any weight, or combination vehicles with a combined gross weight over 26,000 pounds. Carriers must retain fuel and distance records for four years after the return was due or filed, whichever is later.