Free tool
IFTA fuel tax calculator (estimator)
IFTA taxes fuel where you drove it, not where you bought it. Enter miles and gallons for each jurisdiction and the official tax rate, and see what you owe or are owed before the filing date.
Result
Runs in your browser. Nothing you type is sent anywhere. Example numbers are invented (EXAMPLE VALUES). This is a calculator, not financial, tax or legal advice.
Formula table
| Quantity | Formula | Note |
|---|---|---|
| Fleet mpg | all miles / all gallons bought | Across every jurisdiction. |
| Taxable gallons | jurisdiction miles / fleet mpg | Fuel you burned there. |
| Net taxable gallons | taxable gallons - gallons bought there | Positive means you owe, negative a credit. |
| Net tax | net taxable gallons x rate, to the cent | Per jurisdiction, then summed. |
Worked example (invented numbers)
Three jurisdictions with invented rates ($0.20, $0.19, $0.285 per gallon; these are not real rates). TX 4,200 miles and 620 gallons, OK 1,800 miles and 300 gallons, AR 1,000 miles and 250 gallons: 7,000 miles on 1,170 gallons is 5.98 mpg. Texas burned about 702 gallons and 620 were bought there, so $16.40 is owed. Oklahoma is $0.16 owed. Arkansas burned about 167 gallons but 250 were bought there, so it is a $23.61 credit. Net: a $7.05 credit.
What this means for you
If you buy most fuel in a cheap state but drive in expensive ones, the total comes out as tax owed. The number is money your pump receipts already hide: set it aside as you go, not on filing week.
Rates are verify items. They change by quarter. Take them from the IFTA, Inc. tax rate matrix (iftach.org) and check them against your base jurisdiction before relying on the result. Surcharges, minimums and rounding follow your base jurisdiction's rules, which this page does not model.
Related tools
Questions
Where do I find the tax rates?
In the IFTA rate matrix published for each quarter on the IFTA, Inc. site, and by your base jurisdiction. We do not pre-fill rates because they change and we have not verified them for the current quarter.
Can I file with this?
No. It is a planning estimate. Your return follows your base jurisdiction's forms and rules.
Related: IFTA records guide, compliance calendar pilot.
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