To fill out IFTA quarterly reports, you calculate your fleet’s average miles per gallon for the quarter, then use that figure on the IFTA-101 schedule to determine taxable gallons, tax-paid gallons, and net tax owed for each jurisdiction you operated in, before totaling everything on the IFTA-100 summary and submitting it to your base jurisdiction with payment. The math is straightforward once your records are in order. Getting the records in order is where most of the work lives.
Pull Your Records Before You Open the Form
The return is arithmetic on top of two data sets: distance and fuel. Both need to cover the full quarter and both need to be broken out by jurisdiction.
Distance records show, for every trip, the date, origin and destination, route, and beginning and ending odometer readings, with total trip distance split by jurisdiction. Fleet summaries should roll those trips up by vehicle, by month, and by quarter. If you use paper trip reports, drivers record all of this manually. If you use an electronic tracking system, it must ping GPS at least every 10 minutes while the engine is running, and each ping needs the date and time, latitude and longitude to four decimal places, the ECM odometer reading, and the vehicle unit number or VIN. Auditors will not accept GPS data as a PDF or screenshot; export it as CSV, XLS, or a delimited text file.
One warning if you recently added ELDs for hours-of-service compliance: an ELD that meets FMCSA rules does not automatically meet IFTA recordkeeping requirements. The ping frequency and data fields differ. Confirm with your vendor before you rely on it for the return.
Fuel purchase records need a receipt for every retail purchase showing the date, seller’s name and address, gallons, fuel type, price per gallon or total, and the vehicle unit number. Credit card statements alone will not do. Bulk fuel drawn from your own tanks needs its own allocation records showing how the fuel was distributed across vehicles. Summarize fuel by jurisdiction, by vehicle, monthly and quarterly. Those summaries are what you’ll type into the form.
Look Up the Quarter’s Tax Rates
Fuel tax rates change every quarter and every jurisdiction sets its own rate for each fuel type. Pull the current quarter’s rates from the official IFTA Tax Rate Matrix published by IFTA, Inc. before you start filling in numbers. The matrix covers diesel, gasoline, propane, CNG, LNG, and other fuel types for all member jurisdictions.
Watch for surcharges. Indiana, Kentucky, and Virginia impose surcharges on top of their base fuel tax rates, and they show up as separate line items in the matrix. If you traveled through a surcharge jurisdiction, you’ll add a separate line on your schedule using the same mileage and gallons but applying the surcharge rate.
Fill In the Identification Block
The top of the IFTA-100 asks for your legal business name as it appears on your IFTA license, your IFTA identification number, and your mailing address. The ID number is usually your federal EIN, but some jurisdictions assign their own. Match your license exactly. Mismatches slow processing.
Calculate Your Fleet Average MPG
This is the number the rest of the return hinges on. Divide total miles driven across all jurisdictions during the quarter by total gallons purchased during the same quarter. Follow the form’s rounding rule; some jurisdictions want two decimal places, others want four.
A quick example: 120,000 total miles divided by 20,000 total gallons is a fleet average of 6.00 MPG. That single figure applies uniformly to every jurisdiction on the schedule.
Complete the IFTA-101 Schedule
The IFTA-101 has one row for every jurisdiction you entered during the quarter, plus separate rows for any surcharges. For each row, fill in the following:
- Total miles in the jurisdiction. Pulled straight from your distance records and fleet summaries.
- Taxable gallons. Divide the jurisdiction’s miles by your fleet MPG. At 6.00 MPG, 15,000 miles in a jurisdiction produces 2,500 taxable gallons.
- Tax-paid gallons. The gallons you actually purchased in that jurisdiction, supported by receipts.
- Net taxable gallons. Subtract tax-paid gallons from taxable gallons. Positive means you owe; negative means a credit.
- Tax rate. The current quarter’s rate for that fuel type in that jurisdiction, from the matrix.
- Tax or credit due. Net taxable gallons multiplied by the tax rate.
The logic underneath all of this is a settlement. If you burned more fuel in a jurisdiction than you bought there, you didn’t pay enough tax at the pump and you owe the difference. If you bought more fuel there than you burned, you overpaid at the pump and you get a credit. The return just squares up the difference.
Total the IFTA-100 and Pay
Once every jurisdiction has a row, including any surcharge rows, the bottom of the schedule totals net tax due or net credit. That figure carries to the IFTA-100 summary. Owe a balance, and you submit payment with the return. Net credit typically rolls forward to offset next quarter’s balance, though some jurisdictions will refund it on request.
Most jurisdictions offer online filing through a secure tax portal, either through manual entry or an upload from fleet management software. Online systems catch math errors before submission, which is a real advantage over paper. Paper filers mail the completed forms to the address the base jurisdiction specifies. Payment is due at the same time as the return. Electronic funds transfer, ACH withdrawal, and credit card are common; paper filers can usually mail a check. Save the confirmation or receipt as proof of timely filing.
File Even With Zero Activity
If you hold an IFTA license, you file every quarter, even when your trucks didn’t move. A return showing zero miles and zero gallons is still a required filing. Skipping a quarter because there was no activity is treated as a failure to file, and it triggers the same penalties and eventual license suspension.
Deadlines and Late Penalties
Returns are due on the last day of the month after each quarter closes:
- Q1 (January–March): April 30
- Q2 (April–June): July 31
- Q3 (July–September): October 31
- Q4 (October–December): January 31
When a deadline lands on a weekend or legal holiday, filing on the next business day is timely. What counts is the electronic submission timestamp or the postmark for mailed returns.
Filing late costs $50 or 10% of the tax due, whichever is greater. Interest accrues on top of the penalty at an annual rate that IFTA, Inc. sets each January. The 2026 rate is 9%, which accrues monthly at 0.75% of the outstanding balance, starting the day after the deadline and compounding until paid. A small balance grows fast over a few months of neglect. Repeated failures to file or pay can lead to suspension or revocation of your IFTA license, which leaves your vehicles unable to cross jurisdictional lines without buying individual trip permits.
Fixing a Return After You File
If you find an error after submitting, file an amended return through the same channel you used the first time. Online portals will flag that you’re amending a period already reported. Common reasons are unreported miles, fuel receipts missed in the original filing, and jurisdiction assignment errors in the distance records.
File amendments quickly. If you’re claiming a refund, most jurisdictions have a statute of limitations that closes the window on overpayments. If you’re reporting additional tax, interest has been running since the original due date, so waiting only makes it more expensive.
Keep the Records for Four Years
Every record used to prepare a return, including trip records, fuel receipts, fleet summaries, and electronic data exports, must be kept for at least four years from the due date of the return or the date it was filed, whichever is later. Your base jurisdiction can audit any time inside that window. If you can’t produce records on request, auditors will disallow tax-paid credits for undocumented fuel, which means you’ll owe the full tax on every mile driven in that jurisdiction as if you never bought fuel there. The resulting assessment plus interest can far exceed what you originally owed.