| State / Province | Miles driven | Gallons purchased | Tax rate ($/gal) | Taxable gal. | Tax due / credit | |
|---|---|---|---|---|---|---|
| – | – | |||||
| – | – | |||||
| – | – |
Estimate only. Enter the current quarter's rate for each jurisdiction from the official IFTA rate table. Surcharges and rounding rules can change the filed amount. Nothing you type is stored or sent anywhere.
How the IFTA Calculation Works
- Add your miles driven and gallons purchased in each state or province for the quarter.
- Fleet MPG is total miles ÷ total gallons.
- Taxable gallons in each state are that state's miles ÷ fleet MPG.
- Net taxable gallons are taxable gallons − gallons purchased there. Multiply by the state's tax rate. A positive result is tax due, a negative one is a credit.
- Add up every jurisdiction to get your net amount due or refund.
Tax rates change each quarter, so enter the rates from the official IFTA rate table for the quarter you are filing. For a worked example, read how to calculate IFTA tax step by step.
Where to Get Your Miles
Miles by state are the hardest input. Pull them from your ELD or GPS export, your trip sheets, or let iFuelTax calculate state miles from each trip's origin and destination. See our IFTA mileage calculator guide and the comparison of calculators vs GPS tracking.
Spot Potential Audit Risks Before You File
Certain patterns in your data can increase audit scrutiny:
- Large credits in a single jurisdiction
- Big shifts in MPG compared to prior quarters
- Missing miles in states you routinely cross
Learn more in the IFTA Audit Survival Guide.
From Calculator to Automated IFTA Reporting
This calculator is perfect for quick estimates and one-off checks. As your fleet grows, manual entry becomes time-consuming and error-prone. With IFTA & IRP Tax Software, you can:
- Import trip and fuel data directly from your systems
- Run the same calculations automatically every quarter
- File with confidence, backed by a complete audit trail