IFTA fuel tax calculator
Add a row for each jurisdiction you drove in this quarter: miles, gallons bought and the current tax rate. You get tax due or credit for each, and the total.
By Gustavo · Updated October 2026
EXAMPLE rates are filled in. Replace them with this quarter's rate for each jurisdiction from the IFTA tax rate matrix before you rely on the result.
| Jurisdiction | Miles | Gallons bought | Rate $/gal | Remove |
|---|---|---|---|---|
ESTIMATED CREDIT
Fleet MPG 6.82
- TX taxable 616 gal
- -$16.80
- OK taxable 264 gal
- $21.66
- KS taxable 220 gal
- -$7.80
Fuel tax follows the miles. We plan lanes and fuel stops with you, and you approve every load.
How to calculate IFTA fuel tax
- Fleet MPG = total miles in all jurisdictions / total gallons bought.
- Taxable gallons in a jurisdiction = miles driven there / fleet MPG.
- Net tax = (taxable gallons - gallons bought there) x that jurisdiction's rate.
- Total = the sum. Positive is owed; negative is a credit.
You paid fuel tax at the pump in each state where you bought fuel. IFTA settles the difference between where you bought it and where you burned it.
SOURCE: Rates change every quarter: use the IFTA tax rate matrix for the quarter you're filing. The rates in the tool start as examples.
Worked example
| State | Miles | Gallons bought | Taxable gallons | Net |
|---|---|---|---|---|
| TX | 4,200 | 700 | 616 | -$16.80 |
| OK | 1,800 | 150 | 264 | $21.66 |
| KS | 1,500 | 250 | 220 | -$7.80 |
| Total | 7,500 | 1,100 | MPG 6.82 | -$2.94 |
The truck bought more fuel in Texas and Kansas than it burned there, and less in Oklahoma. Oklahoma is owed tax; the other two give credits. The net is a small credit.
Good and bad results
A big tax due usually means you bought cheap fuel in low-tax states and burned it in high-tax ones. That can still be the right call, because the pump price includes the tax. Compare total cost, not just the IFTA line.
A big credit is fine, but check the inputs first: a missing fuel receipt or miles logged in the wrong state are common errors.
Records that make the return easy
- Miles by jurisdiction for every trip, from your ELD or trip sheets.
- Every fuel receipt, with date, location, gallons and the vehicle.
- Keep records for four years. Auditors can ask for them.
Common IFTA mistakes
- Using each truck's own MPG when the return asks for the fleet figure. Follow your base jurisdiction's instructions.
- Leaving out reefer fuel bought in the same receipt as road fuel. Reefer fuel is often handled separately; split it on the receipt.
- Forgetting toll roads and short hops. Every mile in a jurisdiction counts, even a few miles across a state line.
- Late filing. Penalties and interest add up fast, and a return is due even with no miles.
- Missing decals. Each qualified truck carries current IFTA decals and a copy of the license.
Fuel, lanes and dispatch
Where you buy fuel and which lanes you run both show up on the IFTA return. We plan loads and reloads around your lanes and your fuel stops, so the miles make sense on the return as well as the settlement. You approve every load, and the rate confirmation comes straight to you. Run a single trip with the trip fuel cost calculator, or see our rates and fees.
Questions about this calculator
Q01How do you calculate IFTA?
Divide total miles by total gallons for your fleet MPG. For each jurisdiction, divide its miles by that MPG to get taxable gallons. Subtract the gallons you bought there, then multiply by that jurisdiction's rate. A positive number is tax due, a negative one is a credit.
Q02Who has to file IFTA?
Carriers operating qualified motor vehicles in more than one IFTA jurisdiction: vehicles with two axles and over 26,000 lb, three or more axles at any weight, or combinations over 26,000 lb. Some lighter rigs, like many non-CDL hotshots, may not qualify. Ask your base jurisdiction.
Q03When are IFTA returns due?
Quarterly, by the last day of the month after the quarter ends: April 30, July 31, October 31 and January 31. A return is due even for a quarter with no miles.
Q04Where do I find current IFTA tax rates?
IFTA, Inc. publishes the tax rate matrix each quarter, and your base jurisdiction's return uses it. Some jurisdictions add a surcharge or change rates mid-year.
Q05Is this an IFTA mileage calculator?
It takes the miles you already logged per jurisdiction. Your ELD or trip records should give you those miles by state.