IFTA Calculator

IFTA tax is based on the fuel you used in each jurisdiction, not where you bought it. Divide total miles by total gallons to get one fleet MPG. For each jurisdiction, divide its taxable miles by that MPG to get taxable gallons, subtract the tax-paid gallons you bought there, and multiply by the jurisdiction's rate. Add a surcharge where one applies, then add up every line to get your net tax due or credit.

The quarterly return uses one average fuel consumption figure for the whole period: total miles in all jurisdictions, including non-IFTA ones, divided by total gallons placed in the tank, rounded to two decimal places. One MPG spreads your fuel use across jurisdictions in proportion to the miles you drove in each.

Each jurisdiction taxes the fuel used on its roads. If you bought more tax-paid fuel in a jurisdiction than your miles there used, you have already paid that jurisdiction's tax on the difference, so the line becomes a credit. Where you drove more than you fueled, you owe the difference. Credits on some lines reduce the tax due on others when the lines are added up.

A surcharge is an extra tax a few jurisdictions charge on top of their fuel tax. It is calculated on all taxable gallons used in the jurisdiction, and fuel bought there cannot reduce it, so it is never a credit. In the third quarter of 2026, Kentucky and Virginia charge a surcharge on diesel and most other fuels, and Indiana charges one on propane. The calculator reads this from each quarter's rate table.

Yes, but in different ways. Oregon is an IFTA member, but it taxes heavy trucks mainly through its weight-mile tax, so it has no IFTA diesel rate: report the miles, and the tax on that line is $0.00. Alaska and Washington, D.C. are not IFTA members. Miles and fuel there are not taxed on the IFTA return, but they still count toward your total miles, total gallons, and fleet MPG.

Returns are due on the last day of the month after each quarter ends: April 30, July 31, October 31, and January 31. When that day falls on a weekend or holiday, the due date moves to the next business day. The third-quarter 2026 return is due Monday, November 2, 2026, because October 31 is a Saturday. Late returns can be charged interest and penalties, which this calculator does not include.

Keep the records behind every number you report: trip records for each vehicle showing dates, origin and destination, routes, odometer readings, and miles by jurisdiction, and fuel receipts showing the date, the seller, the gallons, and the vehicle the fuel went into. Base jurisdictions such as New Jersey and Idaho require you to keep these records for at least four years. A worksheet from this site shows how your numbers were calculated, but it does not replace those records.

Each quarter's rates are compiled from two state agency publications of the IFTA rate tables: Forms IFTA-105 and IFTA-105.1 from New York and Form GAS-1278 from North Carolina. The two are compared cell by cell, and a quarter is published only when every cell matches. Rates are added once each quarter's final tables are out and are rechecked every month for corrections. The worksheet shows the quarter and the date the rates were retrieved.