IFTA Filing Step by Step: Quarterly Fuel Tax Made Simple

What IFTA Is and Why It Exists

The International Fuel Tax Agreement (IFTA) is a system that simplifies fuel tax reporting for commercial vehicles operating in multiple states and Canadian provinces. Without IFTA, you would need to file separate fuel tax returns in every state you drove through, which for an interstate trucker could mean filing 20 to 40 individual state returns every quarter.

IFTA works by collecting all your fuel purchase and mileage data and redistributing tax revenue to each jurisdiction based on the miles you drove there. You file a single quarterly return through your base state (the state where your business is registered), and the IFTA system ensures each state receives its fair share of fuel tax.

You are required to register for IFTA if your qualified motor vehicle (over 26,000 pounds GVW or having three or more axles) operates in more than one IFTA member jurisdiction. All 48 contiguous US states and 10 Canadian provinces are IFTA members. Alaska, Hawaii, and the District of Columbia are not IFTA members, though they may have separate fuel tax requirements.

Registration is done through your base state's department of revenue, motor carrier division, or equivalent agency. The registration is free in most states and provides you with an IFTA license (kept in the truck) and two IFTA decals (displayed on both sides of the cab exterior). Your IFTA license and decals are valid for the calendar year and must be renewed annually.

Record-Keeping Requirements: What You Must Track

IFTA requires you to maintain detailed records of all miles driven and all fuel purchased, organized by jurisdiction (state or province). These records must be retained for four years from the tax return due date and must be available for audit at any time.

For mileage tracking, you must record the date, trip origin and destination, route of travel, beginning and ending odometer or hubodometer readings, and total miles driven in each jurisdiction. Your ELD automatically tracks much of this data, and many ELD platforms generate IFTA-ready mileage reports broken down by state. If your ELD does not provide this feature, you must maintain manual records or use a separate IFTA tracking app.

For fuel purchases, you must keep every receipt showing the date of purchase, vendor name and address, number of gallons purchased, fuel type (diesel, gasoline, gasohol, propane), price per gallon, total amount paid, and the state or province where the fuel was purchased. Digital receipts and scanned copies are acceptable, but you must be able to produce them during an audit.

The most common record-keeping mistake is failing to track fuel purchased at the pump versus fuel consumed from bulk storage. If you have a fuel tank at your base and fill up there, that fuel must still be recorded with the jurisdiction of purchase and the quantity. Some operators also forget to record reefer fuel separately if they have a separate reefer fuel tank, though reefer fuel is generally not subject to IFTA (it depends on the jurisdiction and how the reefer is fueled).

How to Calculate Your IFTA Quarterly Return

The IFTA return calculation follows a logical sequence. Start by compiling your total miles driven during the quarter, broken down by state. Then compile your total fuel purchased during the quarter, also broken down by state. Your overall fuel efficiency (MPG) for the quarter is calculated by dividing total miles driven by total gallons consumed.

For each state, you calculate the taxable gallons consumed in that state: miles driven in that state divided by your fleet MPG. Then you compare taxable gallons consumed to gallons actually purchased in that state. If you consumed more gallons in a state than you purchased there, you owe that state additional tax. If you purchased more than you consumed, that state owes you a credit.

Example calculation for Texas in Q1: You drove 5,000 miles in Texas and purchased 600 gallons there. Your fleet-wide MPG for the quarter was 6.5. Taxable gallons consumed in Texas: 5,000 / 6.5 = 769.2 gallons. You purchased 600 gallons in Texas, so the net taxable gallons are 769.2 - 600 = 169.2 gallons owed. At Texas's diesel tax rate of $0.20 per gallon, you owe Texas $33.84.

Conversely, if you purchased 900 gallons in Texas but only consumed 769.2, you have a credit of 130.8 gallons (900 - 769.2) and Texas owes you $26.16. These credits and debits across all states are netted together, and you either owe a payment or receive a refund for the quarter.

Each state's diesel fuel tax rate is different and changes periodically. IFTA, Inc. publishes the current tax rates for all member jurisdictions, and most IFTA filing software automatically applies the correct rates. Always use the rates for the quarter you are filing, not the current rates.

Filing Deadlines and Penalties for Late Filing

IFTA returns are due quarterly, 30 days after the end of each quarter. The deadlines are: Q1 (January through March) due April 30, Q2 (April through June) due July 31, Q3 (July through September) due October 31, and Q4 (October through December) due January 31. If the due date falls on a weekend or holiday, the deadline extends to the next business day.

Late filing penalties vary by state but typically include a $50 per jurisdiction penalty or 10% of the tax due (whichever is greater), plus interest charges on the unpaid balance. Some states impose additional penalties for chronic late filers. If you miss multiple consecutive deadlines, your IFTA license can be revoked, which means you cannot legally operate in any IFTA jurisdiction.

You must file an IFTA return even if you did not operate during the quarter. A zero-mileage return confirms that you had no taxable activity and prevents your account from being flagged as delinquent. Failing to file a zero return is treated the same as a late filing and carries the same penalties.

Most base states now allow electronic filing through their online portals. Electronic filing is faster, reduces errors, and provides immediate confirmation of receipt. Some states also accept filings through the IFTA, Inc. web portal. Payment is typically made electronically at the time of filing (ACH, credit card, or electronic check). If you owe a balance, the payment is due by the filing deadline. Refunds are typically processed within 4 to 8 weeks.

IFTA Audits: What They Check and How to Pass

IFTA audits are conducted by your base state on behalf of all IFTA jurisdictions. The audit examines your distance and fuel records for a specific period (usually one year) to verify the accuracy of your filed returns. You may be selected for audit randomly, because of discrepancies in your filings, or because of red flags like unusually high MPG (which suggests unreported miles).

The auditor compares your claimed mileage by state against independent verification sources: ELD records, toll records, GPS data, fuel purchase locations (you cannot buy fuel in a state you claim to have never visited), and any available weight station records. They also verify your fuel purchases against your reported purchases and check that your fleet MPG is reasonable for your vehicle type.

A reasonable diesel MPG for an over-the-road semi truck is 5.5 to 8.0. If your IFTA filings show a fleet MPG of 10.0, the auditor will suspect unreported miles (because higher MPG means fewer gallons consumed per mile, which reduces your tax liability). Conversely, a fleet MPG below 4.5 might indicate unreported fuel purchases.

If the audit finds discrepancies, you will receive a notice of assessment showing the additional tax owed plus interest and penalties. You have the right to appeal the assessment and present additional documentation. To prepare for an audit, keep immaculate records: save every fuel receipt, ensure your ELD mileage reports match your IFTA filings, and reconcile your records quarterly before filing.

The best audit defense is accurate, consistent record-keeping. An auditor who finds well-organized records that cross-reference properly will spend less time on your audit and is less likely to dig deeper for problems. An auditor who finds missing receipts, inconsistent mileage, and disorganized records will scrutinize every detail.

IFTA Filing Tips and Software Recommendations

Use IFTA tracking software or apps to automate the most tedious parts of filing. TruckingOffice, Rigbooks, and ATBS all offer IFTA tracking features that import GPS data, calculate state-by-state mileage, and generate filing-ready reports. Many ELD platforms (KeepTruckin/Motive, Samsara, and Geotab) include IFTA reporting as a built-in feature.

Reconcile your fuel receipts weekly rather than waiting until the end of the quarter. A missing receipt from three months ago is almost impossible to reconstruct, but a missing receipt from last week can be retrieved from the truck stop's records or your fuel card statement. Set aside 15 minutes every Sunday to organize receipts and verify mileage.

Use a fuel card (Comdata, EFS, Pacific Pride, or similar) for all fuel purchases. Fuel cards automatically track every purchase with date, location, quantity, and price. Your quarterly fuel card statement serves as a backup to individual receipts and simplifies audit preparation. Cash fuel purchases are harder to document and more likely to cause audit problems.

Keep state-by-state mileage running totals throughout the quarter so you can verify that your ELD or tracking app is capturing data correctly. If you notice that a state you drove through multiple times is not showing any miles, there may be a GPS or data capture issue that needs to be corrected before the quarter ends.

Some states impose surcharges in addition to the base fuel tax. Oregon charges a weight-mile tax instead of a fuel tax for vehicles over 26,000 pounds. Kentucky charges a KYU tax. New York charges an HUT (Highway Use Tax). New Mexico charges a weight-distance tax. These surcharges are not handled through IFTA and require separate filings with each respective state. Make sure you are filing all required reports, not just IFTA.