IFTA is the quarterly fuel-tax return every interstate owner-operator dreads. This page does the tedious part for you — enter your miles and fuel by jurisdiction and get your fleet MPG, net taxable gallons, and tax owed or refund — plus the deadlines and the exact formula.
| Jurisdiction | Miles | Gallons bought | Tax rate $/gal | Net gal | Tax |
|---|---|---|---|---|---|
| — | — | ||||
| — | — | ||||
| — | — |
Enter each jurisdiction's current diesel rate from the official IFTA tax-rate matrix (rates change every quarter). Fleet MPG = total miles ÷ total gallons; gallons used in a state = its miles ÷ fleet MPG; net taxable gallons = used − bought there; tax = net × that state's rate. Estimate only — file through your base jurisdiction.
The International Fuel Tax Agreement covers the lower 48 U.S. states and 10 Canadian provinces. If you run a qualified motor vehicle across state lines, you file one quarterly return with your base jurisdiction, which then divides the fuel tax among the states you drove in. The key idea: you pay fuel tax based on the miles you drove in each state, but you get credit for the fuel-tax you already paid at the pump there — so each quarter you either owe a little or get a refund.
| Quarter | Period | Due date |
|---|---|---|
| Q1 | Jan 1 – Mar 31 | Apr 30, 2026 |
| Q2 | Apr 1 – Jun 30 | Jul 31, 2026 |
| Q3 | Jul 1 – Sep 30 | Oct 31, 2026 |
| Q4 | Oct 1 – Dec 31 | Feb 1, 2027 (Jan 31 is a Sunday) |
If a due date lands on a weekend or holiday, it moves to the next business day. File and pay even a $0 return to stay compliant.
Operators of qualified motor vehicles (generally over 26,000 lbs or 3+ axles) that travel in two or more IFTA jurisdictions. You register in your base state and file quarterly.
Miles driven in each jurisdiction (from your ELD/trip records) and fuel purchases by jurisdiction (keep receipts/fuel-card reports). The calculator above turns those into your numbers.
From the official IFTA tax-rate matrix, updated every quarter. Rates differ by state and by fuel type, which is why this tool lets you enter the current rate per jurisdiction.
Formula and structure per the International Fuel Tax Agreement; deadlines are the last day of the month after each quarter (next business day if a weekend/holiday). Sources: IFTA, Inc. tax-rate matrix and member jurisdiction guidance. Last updated June 2026. Built by TruckMargin — cost tools for owner-operators. Not tax advice.