Idaho Gas Tax

Idaho taxes gasoline at a flat 32.0¢ a gallon, plus a one-cent petroleum transfer fee on all fuels that funds cleanup of petroleum storage tank releases. Fuel is not subject to the state sales tax, and the EIA lists no local option fuel taxes for Idaho.

The rate was last changed on July 1, 2015, when House Bill 312 raised it by 7¢, from 25¢ to 32¢ a gallon, as part of a transportation funding package that also raised vehicle registration fees. The tax is not indexed to inflation or fuel prices, so it stays at the same number of cents per gallon until the legislature changes it.

Idaho’s total state tax of 33.0¢ a gallon is the 20th-highest of the 50 states and D.C., against a 51-jurisdiction average of 33.8¢. With the federal tax of 18.4¢, the combined rate is 51.4¢ a gallon.

How the tax fits with fuel supply and price history is covered on the Idaho gas prices page.

Idaho borders six states, and its 33.0¢ a gallon is in the lower half of that group. Washington charges 60.2¢, Oregon 40.0¢, Utah 38.6¢ and Montana 33.8¢, all more than Idaho. Only Wyoming, at 24.0¢, and Nevada, at 23.8¢, charge less. Three of the higher-tax neighbors, Washington, Oregon and Montana, are also flagged by the EIA as allowing local option fuel taxes that their figures leave out; Idaho is not.

Two of those borders differ a lot. Montana’s rate is less than a cent above Idaho’s, so along the panhandle’s eastern edge the state tax is effectively level. Washington’s is more than one and a half times Idaho’s, which matters where the two states share metro areas: Lewiston faces Clarkston across the Snake River, and Post Falls and Coeur d’Alene sit a short drive from Spokane.

Of the 33.0¢ total, 32.0¢ is excise and 1.0¢ is the petroleum transfer fee. With the federal 18.4¢, the combined rate is 51.4¢; Idaho’s share is a little under two-thirds of that. The state ranks the 20th-highest of 51 and is less than a cent under the 51-jurisdiction average of 33.8¢.

In the EIA's July 2026 table, Washington's 60.2¢ is the highest state total among the 6 states bordering Idaho, and Idaho's 33.0¢ is 27.2¢ below it. Idaho's total is 7.0¢ (EIA table, July 2026) below Oregon's 40.0¢, and it is 5.6¢ below Utah's 38.6¢. Montana reports 33.8¢ (EIA table, July 2026), and Idaho is 0.8¢ below Montana.

Wyoming and Nevada are the bordering states that list less: Idaho is 9.0¢ (EIA table, July 2026) above Wyoming's 24.0¢, and 9.2¢ above Nevada's 23.8¢, the lowest among the bordering states. That leaves 4 of 6 bordering states with a higher state total than Idaho in the EIA's July 2026 table.

Ranked 20th-highest in the EIA's July 2026 table, Idaho has 19 jurisdictions with a higher state total and 31 with a lower one. California, at 73.6¢, holds the highest state total in the July 2026 table, and Alaska, at 9.0¢, holds the lowest. Against the 33.8¢ (EIA table, July 2026) average for the 50 states and D.C., Idaho's total is lower by 0.8¢.

Of Idaho's 33.0¢ (EIA table, July 2026), 32.0¢ is excise and 1.0¢ is other state taxes and fees, which makes excise 97% of the total. In the combined 51.4¢ (EIA table, July 2026) that includes the federal 18.4¢, the state's share is 64%. County and local taxes are not part of any of these July 2026 totals.