IFTA Fuel Tax Calculator
Estimate your IFTA fuel tax liability or credit for a given state based on miles driven and gallons purchased.
Results
Visualization
How It Works
The International Fuel Tax Agreement (IFTA) requires interstate motor carriers to report and pay fuel taxes based on miles driven in each jurisdiction. Rather than buying fuel tax permits in every state, IFTA lets you file a single quarterly return that redistributes fuel taxes based on actual consumption per state. Understanding IFTA is critical for owner-operators to avoid penalties and maximize tax credits.
The Formula
Variables
- Miles Driven — Total miles driven within the state during the quarter
- Fleet MPG — Your overall fleet miles per gallon (used to estimate consumption)
- State Tax Rate — The state's fuel tax rate per gallon
- Gallons Purchased — Total gallons of fuel purchased within the state
Worked Example
You drove 3,000 miles in Texas and purchased 500 gallons there. At 6.5 MPG, you consumed about 461.5 gallons in Texas. With Texas tax at $0.20/gallon, you owe $92.31 in tax but already paid $100.00 at the pump, giving you a $7.69 credit for Texas. This credit offsets taxes owed in states where you drove but bought less fuel.
Practical Tips
- Keep detailed records of every fuel purchase receipt — IFTA auditors require documentation going back 4 years.
- Use a fleet fuel card to automatically track purchases by state for easier IFTA filing.
- File your IFTA return on time each quarter (April 30, July 31, October 31, January 31) to avoid late penalties.
- Consider buying more fuel in lower-tax states when possible to generate IFTA credits in those jurisdictions.
- Track your fleet MPG accurately — an inflated MPG will underestimate consumption and create tax underpayments that trigger audits.
Frequently Asked Questions
What is IFTA and who needs to file?
IFTA is the International Fuel Tax Agreement. Any vehicle with two axles and a gross vehicle weight over 26,000 lbs, or any vehicle with three or more axles regardless of weight, that travels in two or more IFTA jurisdictions must file.
How often do I need to file IFTA returns?
IFTA returns are filed quarterly. Deadlines are the last day of the month following the quarter end: April 30, July 31, October 31, and January 31.
What happens if I get an IFTA audit?
IFTA auditors will examine your fuel purchase records and mileage logs for a selected period. You need to have receipts, trip sheets, and odometer readings. Inadequate records can result in tax assessments based on the worst-case MPG.
Can I get money back from IFTA?
Yes. If you purchased more fuel in a state than you consumed (based on miles driven), you get a credit for that state. These credits offset taxes owed in other states, and net credits may result in a refund.
Do I need IFTA if I only drive in one state?
No. IFTA only applies to vehicles that travel in two or more IFTA member jurisdictions. If you operate exclusively within one state, you pay that state's fuel tax at the pump and do not need an IFTA license.