Washington diesel tax rate is 49.4¢ per gallon for 2026. Calculate your IFTA fuel tax for Washington routes.
Washington's diesel rate is 49.4¢/gal (2Q 2026). 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.
I-5 (Portland OR–Olympia–Seattle–Bellingham–Canada, primary north-south), I-90 (Seattle–Spokane–Idaho, primary east-west), I-82 (Yakima–Kennewick–Oregon), I-405 (Seattle east bypass), US-2 (Everett–Wenatchee–Spokane, northern tier)
Washington's carbon tax and clean fuel standard contribute to the state's elevated effective diesel rate.
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