IFTA fuel tax calculator
Work out this quarter's fuel tax by state
The numbers already in the boxes are examples to show how it works. Replace them with your own.
Only quarters with a published IFTA rate matrix.
Your numbers
$0.56 net tax due
- Total miles
- 5,000
- Gallons bought
- 650
- Fleet MPG
- 7.69
- Net tax due
- $0.56
| State | Taxable gal | Tax-paid gal | Net gal | Rate / gal | Tax |
|---|---|---|---|---|---|
| Iowa (IA) | 104 | 200 | -96 | $0.3250 | $31.20 credit |
| Minnesota (MN) | 390 | 450 | -60 | $0.3260 | $19.56 credit |
| Wisconsin (WI) | 156 | 0 | 156 | $0.3290 | $51.32 |
| Net tax due | $0.56 | ||||
Rates: official IFTA matrix Q3 2026 (final).
Return due Monday, November 2, 2026.
Alaska, Hawaii, DC and the three northern territories aren't in IFTA: their miles count toward fleet MPG but they get no tax line. Oregon is in IFTA but charges a weight-mile tax instead, so its fuel line is always $0.00. Both work the same way on the real return.
The formula
Fleet MPG is every mile you ran in the quarter divided by every gallon of diesel you bought, rounded to two decimals. Each state's taxable gallons are its miles divided by that MPG, rounded to a whole gallon. Take away the gallons you bought in that state, which you already paid its tax on at the pump, to get net taxable gallons. Multiply by the state's rate and round to the cent.
A positive line is tax you owe that state. A negative line is a credit, because you bought more fuel there than you burned there. The lines add up to one net figure: pay it with your return, or carry the credit.
With the example in the boxes, at the Q3 2026 rates: 5,000 miles ÷ 650 gallons = 7.69 MPG. Wisconsin burned 156 gallons and sold you none, so 156 × $0.3290 = $51.32 owed. Minnesota burned 390 and sold you 450, a $19.56 credit. Iowa burned 104 and sold you 200, a $31.20 credit. Net: $0.56 due.
Surcharge states
Kentucky and Virginia charge a surcharge on top of their fuel tax. It is figured on taxable gallons with no credit for fuel bought there, so it never turns into a credit. The calculator gives it its own line, the way the return does. Indiana's diesel surcharge has been zero since July 2018.
What counts
- All miles, loaded and empty, in every state and province. That includes Alaska, Hawaii, DC and the northern territories, which are not in IFTA, and Oregon, which taxes by the mile instead of by the gallon. None of them gets a fuel tax line, but their miles still go into fleet MPG.
- Only diesel that goes into the truck's own tank. Reefer fuel from a separate tank and DEF stay off the return.
- Gallons by the state on the receipt, from fuel-card statements or pump receipts. Keep them: an auditor will ask.
- This calculator does not take out exempt miles, such as toll roads some states don't tax. If you have them, your real bill is a little lower.
Due dates
The return is due the last day of the month after the quarter ends: April 30, July 31, October 31 and January 31. When that falls on a weekend it moves to Monday, so Q3 2026 is due Monday, November 2. File even when you owe nothing. A late return costs $50 or 10% of the net tax, whichever is more, plus interest every month.
Rates come from the official IFTA rate matrix for the quarter you pick, diesel only: gasoline, propane, LNG and CNG rates are not included. This follows the usual IFTA rounding; a few base states round slightly differently, and your base state's return is the final word. General information, not tax advice.
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