Washington Gas Tax Increase: Rates, Escalator, and Refunds

Washington’s gas tax increased to 55.4 cents per gallon for gasoline and 58.4 cents per gallon for diesel on July 1, 2025, a 6-cent jump from the previous 49.4-cent rate under Senate Bill 5801.¹ Starting July 1, 2026, the rate will climb automatically by 2 percent every year, so this is the last time the legislature will need to pass a bill just to raise the tax.

What Changed in July 2025

Under RCW 82.38.030, Washington charges a flat per-gallon tax on motor vehicle fuel and diesel. The rate is fixed in cents, not tied to the pump price, so the state collects the same amount whether gasoline sells for three dollars or five.²

Senate Bill 5801, sponsored by Sen. Marko Liias and passed with bipartisan support in the 2025 session, raised the gasoline rate by 6 cents and added a separate 3-cent surcharge on diesel on top of that. The package is projected to raise roughly $3.2 billion over six years, with the revenue directed into the Move Ahead WA Account for state transportation projects. Five percent of the new fuel tax money is set aside for local governments.³

The 2 Percent Annual Escalator Starts July 2026

The change with the longest reach is the inflation adjustment written into SB 5801. On July 1, 2026, and every July 1 after that, the gasoline tax rises by 2 percent, compounding annually.⁴ At the current rate, that works out to roughly a penny per gallon in the first year, with the increment growing slowly as the base rises.

Before SB 5801, raising the gas tax required the legislature to pass a bill and set a specific new number. Now the rate grows on autopilot. Lawmakers no longer face a politically visible vote each time construction costs outpace revenue, and drivers no longer see a clean “before” and “after” moment. The practical effect is that Washington’s gas tax will not stay flat for long stretches the way it used to.

Diesel Has Its Own Timeline

Diesel buyers should track three separate milestones on top of the annual 2 percent adjustment:

July 2025: diesel set at 58.4 cents per gallon, which is the gasoline rate plus a 3-cent surcharge.
July 2028: an additional 3-cent surcharge takes effect, putting diesel 6 cents above the gasoline rate.
July 2029: the full 6-cent diesel differential begins its own 2 percent annual adjustment.⁵

Between 2028 and 2029, in other words, diesel picks up a step increase that gasoline does not, and after that both fuels index together.

What You Actually Pay Per Gallon

Washington’s state tax sits on top of the federal excise tax, which is 18.4 cents per gallon on gasoline and 24.4 cents per gallon on diesel. For the July 2025 through June 2026 period, that brings the combined state-plus-federal tax to 73.8 cents on a gallon of gasoline and 82.8 cents on a gallon of diesel.¹ The federal rate has not moved since 1993 and is not indexed for inflation.

Washington’s Climate Commitment Act also adds an indirect cost to fuel through its cap-and-invest auctions, but that cost is separate from the fuel excise tax, does not appear on your receipt as a tax line, and fluctuates with quarterly auction results rather than being set by statute.⁶ Voters rejected Initiative 2117, which would have repealed the program, in November 2024 by roughly 62 to 38 percent, so the CCA remains in effect alongside the higher gas tax.

Where the Money Has To Go

If you’re wondering whether the extra 6 cents can be spent on anything other than roads, the Washington Constitution’s answer is no. Article II, Section 40, the 18th Amendment approved by voters in 1944, requires that all revenue from motor vehicle fuel excise taxes be deposited in a special fund and used exclusively for highway purposes.⁷

“Highway purposes” is defined narrowly in the Constitution itself: building and maintaining public roads, bridges, and city streets; acquiring rights-of-way; operating traffic signals, movable bridges, and highway ferries; the State Patrol’s policing of highways; administrative and engineering costs; debt service on transportation bonds; and refunds for tax paid on off-highway fuel.⁷ The legislature cannot move fuel tax money to schools, health care, or the general fund without a constitutional amendment approved by voters. That restriction is why every major gas tax increase in Washington arrives packaged with a transportation project list.

Refunds If You Paid Tax On Off-Highway Fuel

If you paid the state fuel tax on gasoline or diesel that never touched a public road, RCW 82.38.180 lets you claim a refund. Qualifying uses include agricultural equipment, commercial fishing vessels, stationary engines, and road construction equipment, among others. Separate exemptions cover fuel sold to the federal government, fuel exported out of state, fuel sold to federally recognized tribes under compact, and fuel sold to nonprofit school bus operators, transit services, and passenger-only ferry services.⁸

To claim a refund, set up an account with the Department of Licensing either online through License Express or by mailing a paper Fuel Tax Refund Permit Application. Once the account is active, you file individual refund claims online or on the form the department sends you.⁹

Two rules trip people up. You have 13 months from the date of the fuel purchase to file your claim; after that, the money is gone. And you must have paid at least $20 in fuel tax during the claim period to qualify. Keep your fuel invoices, because the department requires them as supporting documentation.⁹

If You Drive An Electric Vehicle

Electric vehicle owners don’t pay the gas tax, but Washington charges annual registration surcharges to make up part of the difference. Battery electric vehicles currently owe $225 per year on top of standard registration, made up of a $100 electric car fee, a $50 electric car fee, and a $75 transportation electrification fee.¹⁰ For comparison, a driver buying 500 gallons of gasoline a year pays about $277 in state fuel tax at the current 55.4-cent rate.

SB 5801 also phases in higher vehicle weight fees for both gas and electric vehicles starting in 2026, so registration bills will rise regardless of what you drive.³

1
Washington Department of Revenue. Motor Vehicle Fuel Tax Rates
2
Washington State Legislature. RCW 82.38.030
3
Washington State Senate Democrats. Legislature Approves Bipartisan Plan to Fund Washington State Transportation Future
4
Washington State Legislature. Senate Bill Report SB 5801
5
Washington State Fiscal Information. ESSB 5801 Revenue Summary
6
Washington State Department of Ecology. Cap-and-Invest
7
Washington State Legislature. Constitution of the State of Washington
8
Washington State Legislature. RCW 82.38.180
9
Washington State Department of Licensing. Fuel Tax Refunds
10
Washington State Department of Licensing. Calculate Vehicle Tab Fees