The Washington state gas tax is 55.4 cents per gallon as of July 1, 2025. Add the 18.4-cent federal excise tax and you pay 73.8 cents in taxes on every gallon of gasoline you buy at the pump. Both charges are built into the posted price, so there is no separate line item. A third cost, tied to the state’s cap-and-invest carbon program, also sits inside the price you pay, but it moves with carbon auction results rather than staying fixed.
What You Pay Per Gallon Right Now
The state rate is set under RCW 82.38.030 and runs through June 30, 2026 at its current level.1Washington State Legislature. Washington Code 82.38.030 – Tax Imposed – Rate – Incidence – Allocation of Proceeds The federal rate has sat at 18.4 cents since 1993 and is not indexed to inflation.2Federal Highway Administration. Federal Revenue
For the period July 2025 through June 2026, the combined per-gallon tax is:
- Gasoline: 73.8 cents (55.4 state + 18.4 federal)
- Diesel: 82.8 cents (58.4 state + 24.4 federal)
This is a fixed amount per gallon, not a percentage. Whether gas costs $3 or $5, the tax on each gallon stays the same.3Washington Department of Revenue. Motor Vehicle Fuel Tax Rates
Scheduled Increases Starting July 2026
The 6-cent jump that took effect on July 1, 2025 was part of the Move Ahead Washington transportation package, and that same law built in an automatic annual escalator. Starting July 1, 2026, the state fuel tax rate rises by 2 percent each year, rounded to the nearest tenth of a cent.4Washington State Legislature. RCW 82.38.030 – Tax Imposed – Rate – Incidence – Allocation of Proceeds For gasoline, that pushes the state portion from 55.4 cents to roughly 56.5 cents in July 2026, with another step up every year after.
Diesel is scheduled for a steeper path. A 3-cent-per-gallon increase hits in 2026 and another 3-cent increase in 2028, both on top of the 2 percent annual escalator.
The Climate Commitment Act Adds More to the Price
The number at the pump reflects more than the excise tax. Washington’s Climate Commitment Act, codified in RCW 70A.65, created a cap-and-invest system that requires fuel distributors to buy carbon allowances at state auctions. Distributors pass the cost of those allowances through to the price you pay.
Voters had a chance to repeal the program through Initiative 2117 on the November 2024 ballot and rejected it by a wide margin. The per-gallon impact fluctuates with auction prices rather than sitting at a fixed rate. Estimates have generally run between 25 and 50 cents per gallon depending on the quarter’s auction results, so the share of your pump price tied to this program shifts throughout the year.
Where the Tax Revenue Goes
The 18th Amendment to the Washington State Constitution locks fuel tax revenue to highway purposes. The legislature cannot move this money into the general fund or spend it on non-transportation programs.5Washington State Legislature. Washington Code 82.47.030 – Proceeds RCW 46.68 sets out how the money flows from the Motor Vehicle Fund to specific accounts.6Washington State Legislature. Washington Code 46.68.090 – Distribution of Statewide Fuel Taxes
Of the base 23-cent portion, roughly 44 percent goes to the Motor Vehicle Fund for state highway work, about 19 percent to counties, and about 11 percent to cities and towns. Smaller shares fund the Puget Sound Ferry system, the Transportation Improvement Account, the Rural Arterial Trust Account, and the County Arterial Preservation Account.7Washington Department of Revenue. Fuel Tax Later increases are earmarked separately: the 11.9 cents added in 2015 and 2016 feeds the Connecting Washington Account, the 2005 through 2008 increases fund the Transportation Partnership Account, and the 2003 increase pays off transportation bonds from that year.1Washington State Legislature. Washington Code 82.38.030 – Tax Imposed – Rate – Incidence – Allocation of Proceeds
If You Drive an Electric Vehicle
Electric vehicle owners don’t pay the gas tax, but Washington charges flat annual fees at registration renewal instead. A battery-electric vehicle that can travel at least 30 miles on battery alone pays a $100 fee plus a $50 fee, both deposited into transportation accounts, and a $75 transportation electrification fee on top.8Washington State Legislature. RCW 46.17.323 – Electric Vehicle Registration Renewal Fees That totals $225 a year. Electric motorcycles pay $30 annually. Hybrids that can’t do 30 miles on battery power alone pay a separate $75 hybrid electrification fee.
Washington has received federal funding to pilot a per-mile road usage charge as a possible long-term replacement for both fuel taxes and these flat EV fees. If a road usage charge program takes effect, the current flat EV registration fees would be waived for participants.