If you haul across state lines in a qualified vehicle, you owe an International Fuel Tax Agreement (IFTA) return every quarter, including quarters when you owe nothing. This guide walks through the full process: what to track, the math, the deadlines, and the records an auditor will ask for. The Q3 2026 return (July through September) is due Monday, November 2, 2026, because October 31 falls on a Saturday.
This is general information, not tax advice. Your base state's IFTA office makes the final call on your return, so check its rules and portal before you file.
What IFTA actually does
IFTA lets you buy fuel in any member state and pay fuel tax to each state based on the miles you drove there, not where you fueled. You file one return with your base state, and it divides the tax among the other states. You get credit for the tax you already paid at the pump. If you drove more miles in a state than you bought fuel in, you owe the difference. If you bought more fuel than your miles there required, you get a credit.
Do you need an IFTA license?
The IFTA Articles of Agreement define a qualified motor vehicle as one used to carry people or property that has two axles and a gross or registered gross vehicle weight over 26,000 pounds, or three or more axles regardless of weight, or is a combination with a gross weight over 26,000 pounds. The axles counted are on the power unit, not the trailer. If you run a Class 8 tractor or any heavier truck across state lines, you almost certainly need a license. A lighter truck may not qualify. Check your actual registered weight and axle count, and ask your base state if you are close to the line.
If you only run inside one state, you pay that state's fuel tax at the pump and there is no IFTA return.
IFTA deadlines for 2026 and early 2027
Returns and full payment are due on the last day of the month after the quarter ends. If that day is a Saturday, Sunday, or legal holiday, the due date moves to the next business day.
| Quarter | Months | Due date |
|---|---|---|
| Q1 2026 | January to March | Thursday, April 30, 2026 |
| Q2 2026 | April to June | Friday, July 31, 2026 |
| Q3 2026 | July to September | Monday, November 2, 2026 (October 31 is a Saturday) |
| Q4 2026 | October to December | Monday, February 1, 2027 (January 31 is a Sunday) |
You must file even if you did not operate or used no taxable fuel that quarter. File a zero return rather than skipping it.
Step 1: Collect your miles by state
You need total miles and miles in each jurisdiction for every qualified vehicle. Two common sources:
- ELD or GPS reports. Most ELDs can export miles by state. Check the export for gaps, such as days the device was unplugged.
- Trip records. For each trip, record the start and end dates, origin and destination, route, odometer readings, total miles, miles in each state, and the truck's unit number.
Count all miles the truck ran, including empty miles between loads. Deadhead is a real part of your fuel use and of your real cost per mile, and leaving it out makes your fuel economy look better than it is.
Step 2: Total your fuel by state
For each fill-up, keep the receipt or fuel card line. The IFTA Procedures Manual says a retail receipt should show the date, the seller's name and address, the quantity, the fuel type, the price per gallon or total price, and the vehicle the fuel went into. Add up gallons by state for the quarter.
Fuel that did not go into the truck's tank, such as personal use or a separate tank for something else, should not be mixed in. Fuel for a reefer unit can be treated differently depending on how it is stored and on your base state's rules, so ask your base state before you include or leave it out.
Step 3: Calculate your fleet MPG
Fleet MPG = total miles in all states ÷ total gallons in all states
Example: 31,200 miles ÷ 4,875 gallons = 6.40 MPG. If your number looks far from what your truck normally gets, look for missing receipts or missing miles before you file.
Step 4: Find taxable gallons in each state
Taxable gallons = miles in that state ÷ fleet MPG
Example: 6,400 miles in Texas ÷ 6.40 MPG = 1,000 taxable gallons in Texas.
Step 5: Find the net tax in each state
Net tax = (taxable gallons − gallons you bought in that state) × that state's tax rate for the quarter
Tax rates change by quarter, so use the current rate table from IFTA, Inc. or your base state's portal and never reuse an old number. The example below uses made-up rates, for illustration only:
- State A: 1,000 taxable gallons, 800 gallons bought there, rate $0.30. Net tax = (1,000 − 800) × $0.30 = $60 owed.
- State B: 312.5 taxable gallons (2,000 miles ÷ 6.40), 600 gallons bought there, rate $0.40. Net tax = (312.5 − 600) × $0.40 = −$115, a credit.
Add up every state's result. A positive total is what you owe, and a negative total is a credit. Under the Articles of Agreement, you can ask for a refund of a credit, and credits you do not refund can carry forward for up to eight quarters. How that works in practice is up to your base state.
Step 6: File with your base state
Your base state is where your IFTA license was issued. Its tax or motor vehicle agency runs the filing portal. Enter miles and gallons by state, let the system apply the rates, and pay any balance by the due date. If your records are thin, fix that before you file, not after.
Penalties, interest, and your license
Under the Articles of Agreement, a base state may assess a penalty of $50 or 10 percent of the delinquent tax, whichever is greater, for filing late, not filing, or underpaying. Interest also applies to unpaid tax. For U.S. fleets the rate is set at two percentage points above the federal underpayment rate and is adjusted each January 1. Failing to comply with the agreement is grounds for suspension or revocation of your license, and a revoked license means you cannot run interstate on it. Your base state decides what it actually assesses.
Keep your records for four years
The IFTA Procedures Manual requires you to keep the records behind your return for four years from the later of the due date or the date you filed, plus any period covered by waivers or assessments. Good habits that make audits easier:
- Use a fuel card that records the unit number, the state, and the gallons.
- Compare ELD miles with odometer readings every month, not just at quarter end.
- Keep each signed rate confirmation, BOL, and POD. They show where the truck went and when, which helps if you ever have to rebuild a missing day.
- Keep personal fuel purchases off the business card.
New authority? Set this up in week one
A new carrier often starts with a few loads and no system for tracking miles and fuel. If you just got your authority, our new MC authority page explains what dispatch covers. IFTA records are easiest to keep from the first load, and the same trip data helps you work out your real costs in the free RPM calculator.
Where dispatch fits in
A dispatcher does not file your IFTA return or give you tax advice, and Truck Peak does not either. What a dispatcher can do is keep load records clean: pickup and delivery dates, addresses, and miles are on every rate confirmation. That makes it easier to match your ELD miles to real trips. Where you fuel affects the price you pay, but IFTA tax follows the miles you drive in each state, so buying fuel in a low-tax state mostly shifts when you pay, not whether you pay. Compare the pump price before tax, and expect to settle the difference at filing.
If you run a dry van, box truck, or hotshot truck and want help finding loads and checking rate confirmations, we do that. We do not guarantee loads, rates, or revenue.
Sources
Qualified motor vehicle, due dates, penalties, interest, and credits: IFTA Articles of Agreement, effective January 2026. Record retention and receipt contents: IFTA Procedures Manual. Current tax rates: IFTA, Inc. and your base state.