How does the quarterly IFTA return work?

For each quarter you report the miles driven and the fuel purchased in every jurisdiction. The return works out the fuel you used in each jurisdiction from your miles and your fleet MPG, applies that jurisdiction's tax rate, and subtracts the tax you already paid at the pump there. The result is tax owed or a credit, netted across jurisdictions. Returns are due after each quarter ends, so check your base jurisdiction for the exact dates.

What are taxable gallons?

Taxable gallons are the fuel you are treated as having used in a jurisdiction: the miles you drove there divided by your fleet MPG. They are not the gallons you bought there. The difference between taxable gallons and the gallons you bought with tax paid is what turns into tax owed or a credit.

How do I calculate fleet MPG?

Add up the miles driven by all your qualified vehicles in the quarter and divide by the total gallons of fuel they used in that quarter. Use the same fuel type and the same period as the rest of the calculation.

Why does the calculator show the surcharge on its own line?

In the IFTA, Inc. tax rate matrix, Indiana, Kentucky and Virginia list a surcharge separately from the base rate. Showing it as its own line lets you see both parts and check them against your return. In this calculator the surcharge applies to taxable gallons, and the credit for tax paid at the pump uses the base rate only.

Where do the tax rates come from?

IFTA, Inc. publishes a tax rate matrix every quarter. Rates change by jurisdiction and can change during a quarter, so copy the current numbers from the matrix. A blank cell in the matrix means there is no rate for that fuel, which is different from a rate of zero, and the calculator leaves those rows out of the totals.

IFTA calculator

An IFTA calculator estimates your quarterly IFTA fuel tax from the miles you drove and the fuel you bought in each state. Taxable gallons = miles in the state ÷ fleet MPG. Tax due = taxable gallons × the state's rate, minus the tax you paid at the pump.

This free IFTA fuel tax calculator works state by state, shows surcharges as their own line, and writes out every step. Add your miles and gallons for each jurisdiction and the rates from your IFTA, Inc. tax rate matrix. It is an estimate, not a filing. No signup.

Formula: Taxable gallons = miles ÷ fleet MPG. Net = taxable gallons × rate − tax paid gallons × rate. Positive means owed, negative means a credit.
Surcharges: Indiana, Kentucky and Virginia list a surcharge separately, so it is shown as its own line
Rates: From the IFTA, Inc. tax rate matrix, which changes each quarter. Enter the rates for the quarter you are reporting.
Last updated: October 14, 2026

Fleet

Your fuel type and your fleet's miles per gallon for the quarter.

Fuel type

Fleet MPG

mpg

Enter each jurisdiction's tax rate yourself, copied from your IFTA, Inc. tax rate matrix. A blank rate means no rate and that row is left out of the totals.

Jurisdiction 1

Miles driven and fuel bought in this jurisdiction, and its tax rate.

Jurisdiction

Miles driven

Gallons bought, tax paid

gal

Diesel tax rate

$/gal

Fill in the required details above to see your results.

IFTA Calculator

We turn your miles into taxable gallons, apply each jurisdiction's rate and subtract the tax you paid at the pump. Enter your numbers on the left to see it.

Enter your fleet MPG (above 0) to see the estimate.

Meet Bubba,
AI Back-Office
Automation for Fleets

Dispatch, paperwork & compliance - automated.
Just say Hey Bubba!

Start FREE

How to use the IFTA calculator

Have your miles and fuel receipts for the quarter, and your IFTA, Inc. tax rate matrix open.

Set your fuel type and fleet MPG
Choose diesel or gasoline and enter your fleet MPG: total fleet miles divided by total gallons for the quarter.
Add each jurisdiction
Pick the first state you drove in, then use Add a jurisdiction for the rest. Each state can appear once.
Enter miles and gallons
Type the miles driven in the state and the gallons you bought there with tax paid.
Enter the tax rates
Copy each state's rate from your IFTA, Inc. tax rate matrix. Indiana, Kentucky and Virginia also have a surcharge, entered separately. Leave a rate blank if there is no rate.
Read the estimate
See tax due, tax paid at the pump and the net for each state and in total. Positive means owed, negative means a credit.

How an IFTA fuel tax estimate works

IFTA fuel tax is based on where you drive, not where you buy fuel. For each jurisdiction, the fuel you used is estimated as the miles you drove there divided by your fleet MPG. That number of taxable gallons is multiplied by the jurisdiction's tax rate to get the tax due.

You then subtract the tax you already paid at the pump in that jurisdiction. If you bought more fuel there than you used, the result is a credit. If you bought less, you owe the difference. The quarterly return nets all jurisdictions together.

Indiana, Kentucky and Virginia list a surcharge in addition to the base rate. This calculator keeps it as a separate line so you can compare each part with your return.

IFTA calculation example

This example uses a made up rate of $0.30 per gallon to show the steps. It is not a current IFTA rate.

A fleet drives 4,200 miles in one state at 6.5 MPG: 4,200 ÷ 6.5 = 646.15 taxable gallons.
Tax due: 646.15 × $0.30 = $193.85.
The fleet bought 300 gallons there with tax paid: 300 × $0.30 = $90.00 credit.
Net for the state: $193.85 − $90.00 = $103.85 owed. A negative result would be a credit.

What this IFTA calculator does not do

It is an estimate, not a return. Your return is prepared and submitted through your base jurisdiction, and the amounts there are the ones that count. The calculator supports the 48 contiguous states and does not support Canadian provinces. Confirm every figure against your base jurisdiction's return and your tax rate matrix.

FAQ'sFrequently Asked Questions

The International Fuel Tax Agreement (IFTA) is an agreement among the 48 contiguous states and 10 Canadian provinces. It lets a carrier report fuel use and pay fuel tax for all member jurisdictions through one quarterly return filed with its base jurisdiction, instead of dealing with each jurisdiction separately.

More free tools from Bubba

See all free tools

Hey Bubba!

Hey Bubba!