IFTA Calculator
Enter the miles you drove in each state, your MPG and the current tax rates — see the fuel tax owed per state and whether you owe or get a refund.
By the HaulMath editorial team · Updated $1
Key numbers at a glance
| Quarter | Period | Filing deadline | Late penalty |
|---|---|---|---|
| Q1 | Jan 1 – Mar 31 | April 30 | $50–$100 + interest |
| Q2 | Apr 1 – Jun 30 | July 31 | $50–$100 + interest |
| Q3 | Jul 1 – Sep 30 | October 31 | $50–$100 + interest |
| Q4 | Oct 1 – Dec 31 | January 31 (next year) | $50–$100 + interest |
Miles by state (up to 3 states per trip)
Fuel tax rates change — often January 1 and sometimes quarterly. Pull current rates from your base state's IFTA rate matrix (published quarterly at iftainc.com or your state DMV) and enter them above. This tool estimates; your official filing uses your fuel receipts and distance records (ELD/IFTA tracker).
How IFTA actually works (plain English)
IFTA — the International Fuel Tax Agreement — is a deal among 48 U.S. states and Canadian provinces that saves you from filing a separate fuel tax return in every state you drive through. You file one quarterly return with your base state, and it redistributes the money.
The logic is simple even if the paperwork isn't: every gallon of fuel you burn is taxed by the state where it was burned — not where you bought it. Buy cheap fuel in one state and drive through three expensive ones, and your quarterly return will show tax due. Buy fuel in high-tax states and cruise through low-tax ones, and you'll often get a refund.
The formula
Taxable gallons = miles in state ÷ truck MPG. Tax owed = taxable gallons × state rate. Sum across all states, subtract the tax embedded in your pump receipts, and the result is your net IFTA position.
Example: 400 miles in a $0.60/gal state at 6.5 MPG burns 61.5 gallons → $36.93 owed to that state. Do that math for every line of your trip and you have your return.
Three habits that keep IFTA painless
1. Buy fuel where you burn it, roughly. Chasing the cheapest pump price across a state line without checking tax rates often costs more at filing time. Compare price minus tax, plus the rate you'll owe where you're driving.
2. Keep receipts and miles matched. Every fuel receipt needs a corresponding entry in your distance records. Mismatched paperwork is the #1 audit trigger.
3. File on time even when you owe nothing. Late or missing returns rack up penalties fast — usually $50–100 plus interest per late quarter, and repeated misses can suspend your license (and your ability to run legally).
Those deadlines, on one line each — a return is due every quarter even when the net is zero:
| Quarter | Period | Filing deadline | Late penalty |
|---|---|---|---|
| Q1 | Jan 1 – Mar 31 | April 30 | $50–$100 + interest |
| Q2 | Apr 1 – Jun 30 | July 31 | $50–$100 + interest |
| Q3 | Jul 1 – Sep 30 | October 31 | $50–$100 + interest |
| Q4 | Oct 1 – Dec 31 | January 31 (next year) | $50–$100 + interest |
Buying fuel the smart way: price minus tax
The pump price lies to you twice. First, it includes each state's fuel tax — money that comes back to you (or gets collected from you) at filing time anyway. Second, it hides what the next state will charge you for burning its roads. The operator who shops by sticker price systematically overpays.
What seasoned operators compare instead is the net price: pump price minus the state's tax rate, plus a glance at the tax rates of the states ahead on the route. Buying in a high-tax state before crossing into low-tax states is often free money — you prepay tax you were going to owe anyway. The reverse — fueling in a low-tax state to drive through three expensive ones — feels like savings and lands as an IFTA bill four times the difference.
Run the numbers with this calculator when a route crosses three or more rate boundaries, keep receipts matched to miles, and check your quarterly return against these estimates. If they diverge by much, your MPG assumptions — or your receipts file — need attention, and finding that out in October beats finding it out in an audit.
FAQ
How is IFTA calculated?
For each state: taxable gallons = miles in that state ÷ your MPG; tax = gallons × that state's rate. Subtract fuel tax already paid at the pump; the total across states is what you owe or get refunded.
How often do IFTA rates change?
Most states adjust rates on January 1, some quarterly. Pull the current rate matrix from your base state or IFTA Inc. before filing.
What happens if I don't file IFTA?
Penalties of $50–100 plus interest per late quarter, and repeated non-filing can get your IFTA license suspended — which means you can't legally operate interstate until it's reinstated.
Where should I buy fuel to pay less IFTA?
Compare pump price minus that state's tax rate, then look at the rates on the road ahead. Fueling in a high-tax state before crossing low-tax ones is often free money; the reverse shows up four times a year as a bill.
What records do I need for an IFTA audit?
Four things: fuel receipts with no gaps, distance records per state (ELD or GPS trip reports), your MPG calculation, and the returns themselves. Auditors typically ask for four consecutive quarters — mismatched receipts and miles are the #1 finding.