Last updated: May 2026 · Washington IFTA rates current for Q1–Q4 2026
Washington · 49.4¢/gal · High Tax State
Washington IFTA Calculator 2026 — Diesel Tax Rate & Filing
Washington diesel tax rate is 49.4¢ per gallon for 2026. Calculate your IFTA fuel tax for Washington routes and compare neighboring state rates.
Calculate Your Washington IFTA Tax
Gallons consumed in Washington→
Net taxable gallons→
Washington tax rate (2026)→49.4¢/gal
Estimated Washington IFTA→
Positive = amount owed to Washington; negative = credit on your return.
Washington IFTA Rates & Trucking Overview 2026
Washington at 49.4¢/gal is among the highest diesel rates in the US. The Seattle metro is a top-10 freight market driven by Amazon's global headquarters and fulfillment network, major port operations (Port of Seattle and Port of Tacoma combined form the 2nd largest port complex in the US), and Boeing's commercial aircraft production. Despite the high rate, Washington's economic gravity means significant freight must pass through.
Oregon to the south (36.0¢) is 13.4¢ cheaper — fill up in Oregon before entering Washington on I-5. Idaho to the east (32.0¢) is 17.4¢ cheaper for I-90 eastbound runs. For drivers based in Washington, Idaho is the best fuel stop on east-west routes. Washington's carbon tax and clean fuel standard contribute to the state's elevated effective diesel rate.
Washington IFTA — Frequently Asked Questions
What is Washington's IFTA diesel tax rate in 2026?
Washington's diesel rate is 49.4¢/gal — one of the highest in the US. Oregon (36.0¢) and Idaho (32.0¢) are both significantly cheaper. Minimize fueling inside Washington whenever possible.
Who administers IFTA for Washington-based carriers?
Washington IFTA is administered by the Department of Licensing. File quarterly at dol.wa.gov. Washington also has a Hazardous Substance Tax and clean fuel standards that contribute to high effective fuel costs.
Why are Washington's fuel taxes so high?
Washington's diesel rate includes the base excise tax plus contributions to the state transportation fund, a carbon pricing program, and clean fuel standard compliance costs that are passed through to consumers. Washington has consistently ranked among the top 3 highest diesel tax states.
What freight moves through the Port of Seattle/Tacoma?
The combined Seattle/Tacoma port complex handles massive Asia-Pacific container imports — electronics, apparel, furniture, and consumer goods. Exports include agricultural products (wheat, apples, hops), forest products, and manufactured goods. Boeing's 737 and 777 production at Renton and Everett generates specialized air freight and parts logistics.
Fueling tip: Oregon at 36.0¢ saves 13.4¢/gal. Idaho at 32.0¢ saves 17.4¢/gal. Fill completely in Oregon or Idaho before entering Washington. On a 150-gal fill from Idaho, that's $26 saved.