If you've ever crossed a state line in a commercial truck, you owe fuel tax to every state you drove through — not just the states where you actually bought fuel. IFTA (International Fuel Tax Agreement) is the system that handles this accounting across all 48 contiguous U.S. states and Canadian provinces.

For many owner-operators, IFTA feels like one of the most confusing parts of running a trucking business. It doesn't have to be. Here's exactly how it works, what you need to track, and how to avoid the mistakes that lead to audits and penalties.

Who Needs an IFTA License?

You're required to register for IFTA if your vehicle:

  • Has two axles and a gross vehicle weight over 26,000 lbs, OR
  • Has three or more axles regardless of weight, OR
  • Is used in combination and the combined weight exceeds 26,000 lbs

And the vehicle must travel in more than one IFTA jurisdiction (state or province). If you only operate within one state, you follow that state's fuel tax rules instead.

How IFTA Works

The core concept: fuel tax should be paid to the states you actually drive through, in proportion to how many miles you drove there.

Here's the basic flow:

  1. You register for IFTA in your base state (the state where your truck is registered).
  2. Throughout the quarter, you track total miles driven in each state and total gallons of fuel purchased in each state.
  3. At the end of the quarter, you file an IFTA return that calculates how much fuel tax you owe to each state based on miles driven there — and credits you for fuel you already paid tax on at the pump.
  4. You pay any net amount owed (or receive a credit if you overpaid) to your base state, which then distributes the money to the appropriate states.

IFTA doesn't add to what you pay in fuel tax. It just redistributes it. States that you drive through but don't buy fuel in get their share — states where you bought more fuel than you burned get the excess back.

What You Need to Track

Accurate IFTA filing requires two types of records:

Mileage by jurisdiction

For every trip, you need to know how many miles you drove in each state. This is where manual record-keeping gets tedious fast. Most carriers use one of these methods:

  • ELD mileage reports (most accurate and automatically state-separated)
  • GPS-based mileage tracking software
  • Trip sheets with odometer readings at each state line (paper method, error-prone)

Fuel purchases by jurisdiction

Keep every fuel receipt and record the state, date, gallons purchased, and cost. If you use a fuel card, most cards provide monthly reports with this data already organized.

Filing Deadlines

IFTA returns are filed quarterly. The deadlines are:

  • Q1 (Jan–Mar): Due April 30
  • Q2 (Apr–Jun): Due July 31
  • Q3 (Jul–Sep): Due October 31
  • Q4 (Oct–Dec): Due January 31

Late filing results in a penalty of $50 or 10% of the net tax due, whichever is greater. Filing on time even if you can't pay in full is always better than not filing.

Common IFTA Mistakes

Not tracking miles by state

This is the most common error. If you can't document how many miles you drove in each state, auditors will use an average — and their average is rarely in your favor.

Missing or incomplete fuel receipts

Cash fuel purchases without receipts can't be credited. Always get a receipt, and make sure it shows the state, gallons, and date.

Confusing licensed vs. unlicensed jurisdictions

Not all jurisdictions participate in IFTA. If you operate in a non-IFTA state or province, you may need to file separately with that jurisdiction.

Estimating instead of measuring

Estimating mileage is an IFTA audit flag. Use your ELD, GPS, or actual odometer readings — not approximations based on route distance.

How TMS Software Helps

A TMS that tracks mileage per load and per state takes most of the IFTA work off your plate. When every load is entered with origin and destination, the system knows which states were crossed and can generate state-by-state mileage reports at the end of the quarter. Instead of manually compiling trip logs, you export a report and file.

IFTA compliance is one of those tasks that ranges from "annoying but manageable" to "audit risk" depending entirely on whether you're tracking the right data throughout the quarter. The time to get organized is now — not four days before the filing deadline.