IFTA fuel tax calculator
Miles and gallons by jurisdiction in, net tax due or credit out. The rates are the third quarter 2026 diesel rates from the IFTA matrix — July 1 – September 30, 2026, return due October 31, 2026. Kentucky and Virginia surcharges are added for you.
This quarter, by jurisdiction
diesel · 3Q2026
Net tax due — 3Q2026
$8.86
8,400 miles on 1,200 gallons is 7.00 MPG for the fleet.
Total miles
8,400
Total gallons
1,200
Fleet MPG
7.00
truncated to 2 decimals, as on the return
| Jurisdiction | Miles | Taxable gal | Tax-paid gal | Net gal | Rate | Tax due |
|---|---|---|---|---|---|---|
| Texas | 4,200 | 600 | 650 | (50) | $0.2000 | ($10.00) |
| Oklahoma | 1,800 | 257.1 | 300 | (42.9) | $0.1900 | ($8.14) |
| Arkansas | 900 | 128.6 | 0 | 128.6 | $0.2850 | $36.64 |
| Tennessee | 1,500 | 214.3 | 250 | (35.7) | $0.2700 | ($9.64) |
| Total | 8,400 | 1,200 | 1,200 | $8.86 |
Figures in parentheses are credits. Tax due includes the surcharge where one applies.
The line that catches people
Fuel tax is owed where the fuel is burned. The pump price you paid in Oklahoma settled Oklahoma's claim on those gallons; it did nothing for the 900 miles you then ran through Arkansas on them. That is why the Arkansas line above owes money on zero purchases, and why a return that "looks wrong" is usually right. The practical consequence: buying fuel in a cheap-tax state does not save you the tax, only the pump price — and a low pump price in a high-tax state can be the real bargain, because the tax comes back as credit.
Fleet MPG is the number to protect. It is one figure for the whole quarter, all trucks under the licence, and every jurisdiction's taxable gallons come from it. Miss a fuel receipt and MPG goes up, taxable gallons go down everywhere, and the auditor's first question is why your trucks got 9 MPG in March.
third quarter 2026 diesel rates, all 58 jurisdictions
US dollars per gallon, from the IFTA matrix as of 2026-09-03. Canadian rates are the matrix's own US-dollar conversion. Rates change every quarter; twelve changed for 3Q2026.
- Indiana: The 3Q2026 matrix shows Indiana mid-change (a rate row dated 09/06/26). The special-fuel figure on both rows is $0.63; check the matrix before filing.
- Kentucky: Kentucky adds a surcharge on every taxable gallon. It is not collected at the pump, so nothing offsets it.
- Oregon: Oregon has no IFTA fuel tax; it collects a weight-mile tax separately. Oregon miles still count toward your fleet MPG.
- Virginia: Virginia adds a surcharge on every taxable gallon. It is not collected at the pump, so nothing offsets it.
Common questions
How is IFTA fuel tax calculated?
Four steps, all on this page. Divide total miles by total gallons for the quarter to get fleet MPG. For each jurisdiction, divide the miles you ran there by that MPG — those are your taxable gallons. Subtract the gallons you bought there (tax already paid at the pump) to get net taxable gallons, and multiply by that jurisdiction’s rate. Add the lines up: a positive total is tax you owe your base jurisdiction, a negative one is a credit or refund.
Why do I owe tax in a state where I bought no fuel?
Because fuel tax is owed where fuel is burned, not where it is bought. Every mile in a jurisdiction consumes gallons at your fleet MPG, and that jurisdiction taxes those gallons whether you filled up there or not. The reverse is also true: buying more fuel in a state than you burn there produces a credit on that line, which offsets what you owe elsewhere.
What are the Kentucky and Virginia surcharges?
A second tax on every taxable gallon, on top of the per-gallon rate. It is not collected at the pump, so there is no tax-paid credit against it — you owe it on all gallons burned in the state regardless of where you fuelled. On the return it is a separate line under the jurisdiction. This calculator adds it automatically for both states.
Does Oregon count?
Oregon is an IFTA member but collects no fuel tax through IFTA; it runs a separate weight-mile tax that you file with the Oregon Department of Transportation. Oregon miles still count toward total miles — and therefore toward fleet MPG — so put them in. The Oregon line will show zero tax.
When is the IFTA return due?
Quarterly, on the last day of the month after the quarter ends: April 30, July 31, October 31 and January 31. If that falls on a weekend or legal holiday, the next business day. The third quarter 2026 return (July 1 – September 30, 2026) is due October 31, 2026. Late filing or underpayment draws a penalty of $50 or 10% of the tax due, whichever is greater, plus interest.
Which trucks need an IFTA licence?
A qualified motor vehicle: two axles and a gross or registered gross weight over 26,000 lb, or three or more axles regardless of weight, or a combination over 26,000 lb — used in two or more member jurisdictions. Recreational vehicles used for personal pleasure are not included. Under that line you pay fuel tax at the pump and file nothing.
This is a worksheet, not a filing. Your base jurisdiction's return is the document of record — check its rate table against the one above before you send money, especially for a jurisdiction marked with an asterisk. Nothing you type here leaves your browser.
Sources
Every rate and rule on this page was read from the page linked, on the date shown. Nothing here is written from memory.
- IFTA, Inc. — Tax Rate Matrix, 3Q2026 — read 2026-09-03
- IFTA, Inc. — Carrier information (qualified motor vehicle) — read 2026-09-03
- Texas Comptroller — IFTA (due dates, penalty, interest) — read 2026-09-03