Fuel and tax
IFTA Fuel Tax Calculator
Calculates fleet MPG, taxable fuel use, net taxable gallons, tax, surcharge, credits, and estimated net liability from jurisdiction miles and tax-paid fuel. Fleet MPG = total miles / total gallons. Jurisdiction tax = (taxable gallons - tax-paid gallons) x rate, plus applicable surcharge. It uses the IFTA matrix source snapshot captured 2026-08-12; the selected quarter's effective dates are shown in the calculator.
Estimate quarterly IFTA tax due or credit by jurisdiction using the current verified matrix.
Enter operating details
Planning result
Enter valid values, then calculate.
- Detail
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Planning boundary: Estimated tax liability or credit only. Reconcile against the base-jurisdiction return, current matrix notes, exemptions, amendments, penalties, interest, and required rounding before filing.
What this calculator returns
This IFTA calculator estimates quarterly fuel-tax liability for owner-operators, carriers, and fleets that already have jurisdiction mileage and tax-paid fuel totals. It uses the current verified IFTA matrix, calculates one fleet fuel economy, and shows taxable gallons, credits, surcharge, and net tax for every entered jurisdiction without storing trip or receipt data.
How this is calculated
The tool divides total qualified fleet miles by total gallons purchased for the entered fuel type to obtain the quarter fleet MPG. Each jurisdiction mileage total is divided by that fleet MPG to estimate taxable gallons used there.
Tax-paid gallons are subtracted from taxable gallons. The balance is multiplied by the jurisdiction rate. A published surcharge is applied to taxable gallons separately because surcharge treatment can differ from ordinary tax-paid fuel credit treatment. Positive rows indicate estimated tax due and negative rows indicate estimated credit.
Fleet MPG = total miles / total gallons. Jurisdiction tax = (taxable gallons - tax-paid gallons) x rate, plus applicable surcharge.
Variable definitions
- MPG
- Total entered fleet miles divided by total entered tax-paid gallons for the quarter.
- M_j
- Qualified miles traveled in jurisdiction j.
- G_j
- Tax-paid gallons purchased in jurisdiction j.
- R_j
- Official matrix rate for the selected fuel and quarter, expressed in US dollars per US gallon.
- S_j
- Separate published jurisdiction surcharge, when present.
Worked example
A fleet records 1,200 total qualified miles and 200 tax-paid gallons, producing 6.00 MPG. If 600 miles occurred in one jurisdiction, taxable consumption there is 600 divided by 6.00, or 100 gallons.
If 70 tax-paid gallons were purchased there, net taxable gallons are 30. At a $0.31 rate, ordinary tax is $9.30. A separate $0.05 surcharge would add $5.00 on 100 taxable gallons, making the row estimate $14.30. Other jurisdiction credits can reduce the overall net.
How to interpret the result
Use the summary to reconcile total miles, total fuel, and fleet MPG before relying on any jurisdiction row. An implausible MPG often identifies missing receipts, omitted miles, mixed fuel types, or unit errors.
The breakdown is designed for planning and review, not electronic filing. Compare it with base-jurisdiction instructions, exemptions, tax holidays, split rates, reefer fuel treatment, and the return rounding method.
Assumptions and limitations
Planning estimate only. The base-jurisdiction return, exemptions, rounding, penalties, interest, and official instructions control.
- It does not file a return or determine whether a vehicle or trip is IFTA-qualified.
- It assumes all fuel entered is tax-paid and expressed in US gallons and all distance is expressed in miles.
- It does not apply penalties, interest, prior credits, exemptions, tax holidays, exchange settlement, or base-jurisdiction rounding.
- Split-period rate notices and amended matrices must be confirmed against the official return instructions.
Rules and sources used
Frequently asked questions
What MPG does an IFTA return use?
The basic fleet calculation divides total qualified miles in all jurisdictions by total gallons consumed for the fuel type. Base-jurisdiction instructions control the filed method.
Can an IFTA jurisdiction produce a credit?
Yes. When tax-paid gallons exceed estimated taxable use in a jurisdiction, the ordinary tax calculation can be negative and offset tax due elsewhere, subject to filing rules.
Are IFTA surcharges credited at the pump?
A separately published surcharge can be calculated on taxable gallons rather than net gallons. Confirm the matrix notes and base-jurisdiction instructions for the quarter.
Where does the IFTA calculation run?
The IFTA arithmetic runs in the browser. Site measurement and optional subscription features operate separately from the calculator result.