IFTA, Minus the Confusion

The due dates, the real formula, the surcharge states everyone forgets, and the Oregon exception — with the official rate matrix one click away.

Q2 2026 return due July 31 Official matrix linked, never paraphrased Free — no signup

2026–27 due dates

  • Q2 2026 (Apr–Jun): due Friday, July 31, 2026
  • Q3 2026 (Jul–Sep): due Monday, November 2, 2026 (Oct 31 is a Saturday)
  • Q4 2026 (Oct–Dec): due Monday, February 1, 2027 (Jan 31 is a Sunday)
  • Q1 2027 (Jan–Mar): due Friday, April 30, 2027

Weekend/holiday shifts follow the general next-business-day rule — your base jurisdiction's instructions are the final word. File even for quarters with no operations; "zero returns" are still required.

Rates: the official matrix at iftach.org/taxmatrix4 is the only authoritative rate source — Q3 2026 rates are marked provisional there until early September. We link it rather than republish it so you're never filing on a stale copy. Reviewed July 2026

How the math actually works

IFTA isn't a tax on where you buy fuel — it's a tax on where you burn it. The return reconciles the two:

  1. Fleet MPG = total miles in all jurisdictions ÷ total gallons consumed by your qualified vehicles for the quarter. (Consumed — if you run bulk fuel or carry meaningful tank inventory across quarter lines, that's not identical to gallons purchased.)
  2. Taxable gallons per state = your miles in that state ÷ fleet MPG.
  3. Net gallons = taxable gallons − tax-paid gallons you purchased in that state (gallons, from your receipts — not a dollar figure).
  4. Tax or credit = net gallons × that state's rate from the official matrix. Negative = credit. Sum across states = your return.

The three surcharge states

Indiana, Kentucky, and Virginia each have a second line on the matrix: a surcharge on every gallon you consume there. The trap: the surcharge is not reduced by fuel you bought at the pump — buying fuel in Indiana doesn't pre-pay Indiana's surcharge. It's why a driver who fuels heavily in a surcharge state can still owe money there.

Oregon is not an IFTA fuel-tax state

The matrix shows no ordinary fuel rate for Oregon: it runs a separate weight-mile tax with its own permits and reporting. Your Oregon miles still count in fleet MPG, but Oregon taxes are handled outside the IFTA rate math.

Cousins to know about

  • Kentucky KYU — a weight-distance tax of $0.0285/mile for vehicles over 59,999 lb combined license weight (KRS 138.660), on top of the IFTA surcharge. Separate license, separate filing.
  • New York HUT and New Mexico WDT — their own weight-distance regimes with separate registrations.
Why there's no estimator on this page yet: a calculator that skips the surcharge lines, fuel types, or Canadian rates can misstate a real return, and we'd rather give you no number than a wrong one. A full-scope diesel estimator (all jurisdictions, surcharges included, Oregon handled properly) is planned once the current quarter's official rates go final in September.
Sources: iftach.org (matrix & jurisdictions) · drive.ky.gov (KYU rate, KRS 138.660) · Reviewed July 2026