The Hawaii gas tax adds between 50.9 and 58.4 cents to every gallon of gasoline you buy, depending on which island you fill up on. That total combines a 18.4-cent federal excise tax, a 16-cent state tax that is the same statewide, and a county tax that ranges from 16.5 cents in Honolulu to 24 cents in Maui County. A separate barrel tax on petroleum products tacks on roughly another 2.5 cents per gallon.
The Three Layers You Pay
Every gallon sold in Hawaii carries tax at the federal, state, and county level. The federal excise tax is 18.3 cents per gallon plus a 0.1-cent Leaking Underground Storage Tank fee, for a total of 18.4 cents, and it has not changed since 1993.1U.S. Energy Information Administration. Frequently Asked Questions – How Much Tax Do We Pay on a Gallon of Gasoline and Diesel Fuel That money goes to the federal Highway Trust Fund.
The state fuel tax is set under HRS Chapter 243 and applies uniformly across all four counties.2Justia. Hawaii Code 243-4 – License Taxes For gasoline and on-highway diesel, it is 16 cents per gallon.3Department of Taxation, State of Hawaii. Liquid Fuel Tax Base and Tax Collections – January 2026 The tax is imposed on licensed distributors, but distributors pass the cost through to the pump price.
County councils set the third layer by ordinance, and that is where the variation between islands comes from.
Gas Tax Rates by County
Gasoline and on-highway diesel are taxed at the same rates. As of January 2026, the combined state and county rates per gallon are:3Department of Taxation, State of Hawaii. Liquid Fuel Tax Base and Tax Collections – January 2026
- City and County of Honolulu: 16 cents state + 16.5 cents county = 32.5 cents per gallon
- Kauai County: 16 cents state + 17 cents county = 33 cents per gallon
- Hawaii County: 16 cents state + 23 cents county = 39 cents per gallon
- Maui County: 16 cents state + 24 cents county = 40 cents per gallon
Add the 18.4-cent federal tax and the total fuel tax runs from 50.9 cents per gallon in Honolulu to 58.4 cents in Maui County. Maui’s rate sits well above the other counties, and drivers who split time between islands feel the gap right away.
The Barrel Tax on Petroleum
On top of the per-gallon tax, Hawaii imposes an Environmental Response, Energy, and Food Security Tax of $1.05 on every barrel of petroleum product sold by a distributor. A barrel holds 42 gallons, so the cost works out to about 2.5 cents per gallon at the pump.4Justia. Hawaii Code 243-3.5 – Environmental Response, Energy, and Food Security Tax; Uses Aviation fuel is excluded.
The barrel tax revenue is split across several dedicated funds: five cents per barrel for environmental cleanup, four cents to an energy security fund, five cents to an energy systems development fund, and smaller allocations for electric vehicle charging infrastructure and hydrogen fueling stations.4Justia. Hawaii Code 243-3.5 – Environmental Response, Energy, and Food Security Tax; Uses When national comparisons list Hawaii’s state gas tax at around 18.5 cents rather than 16, they are folding this barrel tax into the calculation.
Diesel, LPG, and Alternative Fuels
On-highway diesel is taxed at the same combined state and county rates as gasoline. Off-highway diesel, LPG used off-highway, and aviation fuel each carry a lighter state tax of just 1 cent per gallon, and no county tax applies.
Alternative fuels are taxed as fractions of the diesel rate: ethanol at 14.5%, methanol at 11%, biodiesel at 25%, and liquefied petroleum gas at 33%.5U.S. Department of Energy – Alternative Fuels Data Center. Alternative Fuel Tax Rate Every alternative fuel also carries a flat state tax of one-quarter cent per gallon on top. In practice, the state tax on ethanol comes to about 2.4 cents per gallon, while LPG runs about 5.2 cents at the state level with county taxes added.3Department of Taxation, State of Hawaii. Liquid Fuel Tax Base and Tax Collections – January 2026
What EV Owners Pay Instead
Electric vehicles do not buy gasoline, so Hawaii charges EV owners separately to support road maintenance. Before July 2025, EV owners paid a flat $50 annual surcharge at registration.6Hawaii State Legislature. Hawaii Revised Statutes Chapter 249 – County Vehicular Taxes
Starting July 1, 2025, under Act 222, EV owners can choose between the $50 flat fee and a mileage-based road usage charge of 8 cents per mile, capped at $50 per year. Mileage is tracked through odometer readings taken during the vehicle inspection at registration renewal.7U.S. Department of Energy – Alternative Fuels Data Center. Electric Vehicle Road Usage Charge Program The flat-fee option ends on June 30, 2028, and all EV owners will then pay the per-mile charge. Because the annual charge caps at $50, anyone driving more than 625 miles a year hits the maximum either way. Alternative fuel vehicles that are not fully electric continue to pay the $50 flat surcharge under HRS § 249-31.6Hawaii State Legislature. Hawaii Revised Statutes Chapter 249 – County Vehicular Taxes
Refunds for Non-Highway Fuel Use
If you use taxable liquid fuel for non-highway purposes, such as farming equipment or stationary generators, you may qualify for a refund of state and county fuel taxes paid in excess of 1 cent per gallon.8Cornell Law Institute. Hawaii Code of Rules 18-243-4-01 – Refund of Fuel Taxes in Excess of 1 Cent The refund does not apply to diesel, aviation gasoline, or LPG, because those fuels already carry lower non-highway rates. Fuel that was tax-exempt at the point of sale under HRS § 243-7 or fuel used on public highways is also ineligible. The refund equals qualifying gallons multiplied by the applicable state and county rates minus 1 cent, and detailed purchase and usage records are what support a claim if the Department of Taxation asks.