The Washington state gas tax is $0.554 per gallon, and once you add the $0.184 federal excise tax, drivers pay $0.738 per gallon in combined fuel tax at the pump as of July 1, 2025.1Washington Department of Revenue. Motor Vehicle Fuel Tax Rates Diesel runs higher at $0.828 per gallon combined. Both figures are already baked into the price on the sign, because the tax is collected from licensed distributors before fuel reaches retail stations.2Washington State Legislature. RCW 82.38.030 – Tax Imposed, Rate, Incidence, Allocation of Proceeds Fuel taxed under the per-gallon rate is exempt from state retail sales tax, so you aren’t paying both.3Washington State Legislature. RCW 82.08.0255 – Exemptions, Use of Motor Vehicle and Special Fuel
Current Rates and the Annual Inflation Bump
The state rate jumped six cents in 2025, from $0.494, where it had sat since 2016, to the current $0.554. That change came out of a new transportation revenue package. The same legislation added a 2% annual inflationary adjustment, so the state rate rises each July.
Federal rates haven’t moved since 1993: $0.184 per gallon on gasoline and $0.244 per gallon on diesel.4U.S. Energy Information Administration. How Much Tax Do We Pay on a Gallon of Gasoline and on a Gallon of Diesel Fuel The full breakdown through June 30, 2026:
- Gasoline: $0.554 state + $0.184 federal = $0.738 per gallon
- Diesel: $0.584 state + $0.244 federal = $0.828 per gallon
The Carbon Cost Hidden in the Price
The per-gallon tax isn’t the full story. Washington’s Climate Commitment Act, codified at RCW 70A.65, caps statewide emissions and requires fuel suppliers to buy carbon allowances covering the emissions from the gasoline and diesel they sell.5Washington State Legislature. Chapter 70A.65 RCW – Greenhouse Gas Emissions, Cap and Invest Program Suppliers buy those allowances at quarterly auctions run by the Department of Ecology, then fold the cost into wholesale pricing.
Voters rejected a repeal of the program in November 2024 by roughly 62% to 38% on Initiative 2117. In 2025, the legislature passed HB 1975, setting a hard price ceiling of $80 per allowance for 2026 and 2027. Recent auctions have settled around $50.
Industry estimates put the per-gallon impact at roughly 40 cents for gasoline, though the number moves with each auction. It doesn’t appear as a separate line on your receipt; it’s simply part of what you pay per gallon. Add it to the $0.738 in fixed taxes and the true government-driven load on a gallon of gas in Washington is well over a dollar.
Where the Money Goes
Gas tax revenue is constitutionally locked to transportation. The 18th Amendment to the state constitution requires all motor vehicle fuel tax to go into a dedicated fund and be spent only on highway purposes, including road construction and maintenance, bridges, and the ferry routes that are part of the public highway system.6Washington State Attorney General. Applicability of Article II, Section 40 of the Washington Constitution The legislature cannot redirect that money into the general budget.
RCW 46.68.090 spells out the distribution. The largest share goes to the state motor vehicle fund, with additional portions carved out for counties, cities, the Puget Sound ferry system, and several accounts covering transportation improvements and rural and county arterial preservation.7Washington State Legislature. RCW 46.68.090 – Distribution of Net Tax Amount
Carbon allowance revenue follows a different path. It flows into a climate-dedicated account and funds emission-reduction programs, clean transportation, and environmental justice work rather than traditional road projects.
Refunds for Off-Road and Non-Highway Use
If you buy fuel for something other than driving on public roads, you can claim a refund from the Department of Licensing. Common qualifying uses include fuel for farm machinery and construction equipment, stationary power generators, and fuel exported out of state.8Washington State Legislature. RCW 82.38.180 – Refunds Authorized Diesel used in special mobile equipment, or burned incidentally while moving between two pieces of private property, also qualifies.
Public transit agencies and private nonprofit providers serving people with special transportation needs qualify for exemptions. Government entities and federally recognized tribes operate under separate arrangements; under tribal fuel tax compacts, a portion of the tax stays with the tribe and must be spent on transportation-related purposes within tribal lands.9Washington State Department of Licensing. 2024 Tribal Fuel Tax Agreement Report
You have 13 months from the date of purchase to file a refund claim.10Washington State Department of Licensing. Fuel Tax Refunds Claims can be filed online through License Express or by paper form. You’ll need purchase receipts and records showing the fuel went to a qualifying non-highway use. Miss the 13-month window and the refund is gone.
Electric and Hybrid Vehicle Fees
Drivers who skip the pump still pay for roads, but through annual registration rather than per-gallon tax. Battery-electric vehicles that can travel at least 30 miles on electricity alone pay two fees at renewal totaling $150.11Washington State Legislature. RCW 46.17.323 – Electric and Hybrid Vehicle Registration Fees Electric motorcycles pay $30 annually. Hybrid vehicles that don’t qualify as full EVs pay a $75 annual transportation electrification fee.
Washington has studied a per-mile road usage charge for over a decade, but no mandatory per-mile fee exists for any vehicle type. Research continues, with more findings expected in summer 2026. Until then, EV and hybrid owners pay through registration and everyone else pays at the pump.
How Washington Compares Nationally
Washington consistently ranks among the most heavily taxed fuel markets in the country, trailing only California and competing with Pennsylvania. As of January 2026, state gasoline taxes and fees ranged from 70.9 cents per gallon in California down to 9.0 cents in Alaska, with a national average of 33.5 cents.12U.S. Energy Information Administration. Many States Slightly Increased Their Taxes and Fees on Gasoline in the Past Year Washington’s 55.4-cent state rate sits well above that average, and the carbon program pushes the real cost higher still, though those allowance costs aren’t classified as a tax and don’t appear in most national rankings.