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Washington Gas Tax Calculator

Washington charges 55.4¢/gal on gasoline and 58.4¢/gal on diesel (all state taxes and fees). Combined with the federal tax, drivers in Washington pay 73.9¢/gal total on gasoline.

WA gasoline (combined)

55.4¢

WA diesel (combined)

58.4¢

Federal gasoline tax

18.5¢

18.4¢ excise + 0.1¢ LUST

Combined (gas + federal)

73.9¢

Excise and combined rates are equal for Washington — no separate fees apply.

Federal gasoline excise18.4¢/gal
Federal LUST fee0.1¢/gal
Washington combined55.4¢/gal
Combined rate73.9¢/gal
Rates updated for June 2026

Tax on 15 gallons of gasoline in Washington

Federal tax

$2.77

Washington tax

$8.31

Total tax

$11.08

This calculator is for informational purposes only and does not constitute tax advice. Consult a qualified tax professional for your specific situation. Rates last verified June 2026.

Verify rates on Washington State Department of Licensing — Prorate and Fuel Tax News and Updates

Gas tax per fill-up in Washington

Tank sizeState taxFederal taxTotal tax
10 gallons$5.54$1.85$7.39
12 gallons$6.65$2.22$8.87
15 gallons$8.31$2.77$11.08
18 gallons$9.97$3.33$13.30
20 gallons$11.08$3.70$14.78
25 gallons$13.85$4.63$18.47
30 gallons$16.62$5.55$22.17

Gasoline only. State tax uses combined rate (all fees). Federal includes 18.4¢ excise + 0.1¢ LUST fee.

Washington note: Excise rates reflect the core statutory baseline enacted under Engrossed Substitute Senate Bill 5801. Gasoline rises 2% annually for inflation starting July 1, 2026, while diesel increases by an additional flat 3.00 cents on July 1, 2026. Combined rates match the pure excise baseline as per-gallon retail environmental surcharges are not appended at the pump.

Frequently asked questions

What is the gas tax in Washington?
Washington's state gasoline tax is 55.4¢ per gallon (all fees included) and the diesel tax is 58.4¢ per gallon. Combined with the federal 18.4¢/gal gasoline excise and 0.1¢/gal LUST fee, drivers in Washington pay a total of 73.9¢ per gallon of gasoline in state and federal taxes.
How much gas tax do I pay on a full tank in Washington?
On a 15-gallon fill-up with gasoline in Washington, you pay approximately $8.31 in state taxes (all fees) plus $2.77 in federal tax — a combined total of $11.08 in taxes per fill-up. Use the calculator above to adjust for your tank size.
What is the federal gas tax in 2026?
The federal gasoline excise tax is 18.4 cents per gallon and has been unchanged since October 1, 1993. The federal diesel excise tax is 24.4 cents per gallon. An additional 0.1 cent per gallon Leaking Underground Storage Tank (LUST) fee also applies to both fuels, bringing the combined federal rate to 18.5 c/gal (gasoline) and 24.5 c/gal (diesel). These taxes fund the Highway Trust Fund for interstate highway maintenance and mass transit.
What is the difference between excise rate and combined rate?
The excise rate is the pure statutory per-gallon excise tax set by the state legislature. The combined rate is the total state-level tax burden per gallon as compiled by the EIA, including the excise tax plus environmental fees, petroleum storage tank fees, inspection fees, and in some states an applicable sales tax on fuel. For most states the difference is small (under 2 c/gal), but states like California, Indiana, Illinois, Vermont, and Washington D.C. show significant gaps because they layer sales taxes or large surcharges on top of the excise.
Which state has the highest gas tax?
California has the highest combined state gas tax at 70.9 cents per gallon as of January 1, 2026, per the EIA. This includes the excise tax plus the 2.25% sales tax on gasoline. California also has the highest combined diesel tax at 87.3 c/gal. Illinois (66.4 c/gal gasoline) and Washington (59.04 c/gal) rank second and third.

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