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IFTA Fuel Tax Calculator

Enter the miles you drove and the tax-paid gallons you bought in each state or province for the quarter. The calculator works out your fleet MPG, taxable gallons, the tax or credit for each place and your net tax due, using the official diesel rates from IFTA, Inc. Everything runs in your browser and nothing you type is sent anywhere.

Estimate only. This calculator is an estimate only, not tax advice and not your IFTA return. File with your base state using its own form and the rates for the quarter you are filing, and check with your base state or a tax professional if you are unsure.

How IFTA fuel tax is worked out

IFTA, the International Fuel Tax Agreement, lets a carrier file one fuel tax return a quarter with its base state, which shares the tax out to the other states and provinces. The tax follows the miles: each place gets tax on the fuel you burned there, and you get credit for the tax you already paid at the pump there. This calculator follows the same steps as the return described in the IFTA Procedures Manual (section P720) and in state return instructions such as West Virginia's IFTA return instructions, so you can check it by hand.

• Total miles are all the miles your qualified trucks drove in the quarter, in every place, including non-IFTA and non-taxable miles. Miles are rounded to whole miles.
• Total gallons are all the gallons put in the tanks, tax-paid or not. Gallons are rounded to whole gallons.
• Fleet MPG is total miles divided by total gallons, rounded to 2 decimals (for example, 5.765 rounds to 5.77 and 5.764 rounds to 5.76).
• Taxable gallons for each state or province are its taxable miles divided by your fleet MPG, rounded to a whole gallon.
• Net taxable gallons are taxable gallons minus the tax-paid gallons you bought there. A negative number means you bought more tax-paid fuel there than you burned there.
• Tax or credit is net taxable gallons times that place's rate per gallon. A negative figure is a credit.
• Surcharge, for the states that charge one on diesel, is taxable gallons times the surcharge rate. Tax-paid gallons are not taken off, and a surcharge is never a credit.
• Net tax due is all the taxes, credits and surcharges added up.

The rates come from the IFTA, Inc. tax rate matrix, the official rate chart that IFTA returns use. The quarter and whether the rates are final are shown at the top of the calculator, and every rate is listed in the table under it.

A worked example

These are round example numbers to show the math, not typical miles or fuel use, using the 3rd Quarter 2026 final rates. A truck drives 1,000 miles in Texas, 400 in Oklahoma, 600 in Kentucky and 500 in Virginia, and buys 150 tax-paid gallons in Texas, none in Oklahoma, 100 in Kentucky and 150 in Virginia.

• Total miles: 1,000 + 400 + 600 + 500 = 2,500. Total gallons: 150 + 0 + 100 + 150 = 400.
• Fleet MPG: 2,500 / 400 = 6.25.
• Texas: 1,000 / 6.25 = 160 taxable gallons, minus 150 tax-paid = 10, times $0.2000 = $2.00 due.
• Oklahoma: 400 / 6.25 = 64 taxable gallons, minus 0 = 64, times $0.1900 = $12.16 due.
• Kentucky: 600 / 6.25 = 96 taxable gallons, minus 100 tax-paid = -4, times $0.2200 = -$0.88, a credit. Surcharge: 96 x $0.1050 = $10.08 due.
• Virginia: 500 / 6.25 = 80 taxable gallons, minus 150 tax-paid = -70, times $0.3360 = -$23.52, a credit. Surcharge: 80 x $0.1430 = $11.44 due.
• Net tax due: $2.00 + $12.16 - $0.88 + $10.08 - $23.52 + $11.44 = $11.28.

Tips for a cleaner IFTA quarter

• Log the state line crossings and odometer readings for every trip, or keep your ELD or GPS mileage reports. Miles by state are the base of the whole return.
• Keep a receipt or invoice for every fuel purchase. Under section R1000 of the IFTA Articles of Agreement, you need one to claim credit for tax-paid fuel.
• Count deadhead and bobtail miles in total miles, and all fuel put in the tanks in total gallons, tax-paid or not, as state return instructions such as West Virginia's say.
• Use the rate chart for the quarter you are filing, not the newest one.
• Look over the notices at the top of the calculator. When a state changes its tax partway through a quarter, a one-rate estimate will not match the return for that state.

For more on running your own truck, read the owner-operator vs company driver guide and the trucker per diem guide. To see what fuel does to your take-home, try the owner-operator profit calculator and the load rate checker. To track miles, fuel and tolls week by week, print the free weekly trip log.

Frequently Asked Questions

How do I calculate IFTA fuel tax?

Add up all your miles and all your gallons for the quarter and divide to get your fleet MPG, rounded to 2 decimals. For each state or province, divide its taxable miles by your MPG to get taxable gallons, take off the tax-paid gallons you bought there, and multiply by its rate. Add the results, plus any surcharges, to get your net tax due or credit.

Why do some states show a credit?

A credit means you bought more tax-paid fuel in that state than your miles there burned, so you paid that state more tax at the pump than you owe it. On the return, credits in some places offset tax due in others.

What are the Kentucky and Virginia surcharges?

Kentucky and Virginia each list a diesel surcharge in the IFTA rate matrix, on top of their regular rate. State IFTA return instructions, such as West Virginia's, say the surcharge is figured on taxable gallons with no tax-paid gallons taken off, and it is always tax due, never a credit. The surcharge rates are in the rate table. Virginia's own IFTA return instructions PDF was not available from Virginia DMV when we checked on October 24, 2026, so the surcharge method here is sourced to West Virginia's instructions.

Why does the calculator not figure tax for Oregon?

Oregon has its own weight-mile tax, and the Oregon Department of Transportation says IFTA licensees also file a mileage tax report for it. The IFTA rate matrix lists no Special Diesel rate for Oregon, so the calculator does not estimate Oregon tax. Your Oregon miles and gallons still count toward your total miles, gallons and fleet MPG.

Which quarter's rates does the calculator use?

It uses the quarter shown at the top of the calculator, with its final or preliminary status. IFTA, Inc. posts the rates for each quarter and marks them preliminary until they are final, so the calculator uses final rates whenever they are out.

When is an IFTA return due?

Under section R960 of the IFTA Articles of Agreement, a quarterly return and full payment are due on the last day of the month after the quarter ends: April 30, July 31, October 31 and January 31. If that day falls on a Saturday, Sunday or legal holiday, the next business day is the due date.

Is this my IFTA return?

No. It is an estimate to help you check your numbers and plan. File the real return with your base state, on its form or website, with the rates for the quarter you are filing.