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. Filing late? The penalty is $50 or 10% of net tax due (whichever is greater) plus monthly interest — see the IFTA penalty & interest calculator for the exact cost.
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.
The IFTA late-filing penalty is $50 or 10% of your net tax due, whichever is greater, plus interest on the unpaid tax each month until you pay. Even a $0 or refund return filed after the deadline can owe the $50. See the IFTA penalty & interest calculator to estimate yours.
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 July 2026. Built by TruckMargin — cost tools for owner-operators. Not tax advice.