Oklahoma IFTA Tax Rate — 2026

How Oklahoma IFTA tax is calculated

For every gallon of diesel your truck "burned" inside Oklahoma during the quarter, you owe $0.1900 in IFTA tax. The number of taxable gallons isn't the gallons you bought there — it's the miles you drove inside Oklahoma divided by your fleet's average miles-per-gallon for the whole quarter.

Your IFTA return then nets that against the Oklahoma fuel-tax you already paid at the pump on gallons purchased inside the state. If you ran more Oklahoma miles than you bought Oklahoma fuel, you owe the difference. If you bought more Oklahoma fuel than you ran Oklahoma miles, you get a refund or credit.

Common Oklahoma IFTA filing questions

• Do I file IFTA in Oklahoma if my home base is here? If your IFTA base jurisdiction is Oklahoma, you file your quarterly return with the Oklahoma Department of Revenue (or equivalent). Your filing covers every IFTA jurisdiction you ran in, not just Oklahoma.
• What if I only drove a few miles through Oklahoma? Every IFTA mile counts, even if you only crossed the state. Track them on your trip sheet or ELD report — you'll owe (or get refunded) Oklahoma's share whether you bought fuel here or not.
• What if Oklahoma fuel is cheaper than the IFTA tax? The IFTA rate above is what you owe per gallon "consumed" in Oklahoma. The pump price already includes Oklahoma's state fuel tax — that's what gets credited on your return. If you bought all your fuel in a low-tax state and drove all your miles in Oklahoma, you'll owe the full Oklahoma rate on those gallons at filing time.

Oklahoma IFTA filing deadlines

IFTA returns are due quarterly across all 48 contiguous U.S. states, including Oklahoma:

• 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 filings collect penalties even if you owe nothing — some states charge $50 minimum per late return. File on time even if your net due is $0.