Illinois Gas Tax Goes Up This Summer: How Much More You'll Pay

ILLINOIS — Illinois drivers will be impacted this summer by an increase in the state's gas tax — which is already the second-highest in the nation behind California. Lawmakers are deliberating the increased motor fuel tax as part of the budget for fiscal year 2026, according to state documents.

The gas tax for Illinois drivers is now 47 cents per gallon. Each year, under Illinois law, it goes up based on a formula, and the revenue it generates earmarked for road maintenance and construction.

On July 1, it's poised to increase to 48.3 cents.

The two-part tax falls under the International Fuel Tax Agreement (IFTA). The first part, or Part A, imposes taxes on fuel used "in motor vehicles operating on Illinois public highways and in recreational type watercraft operating on Illinois waters," per 35 ILCS 505/2.

The Part A gas tax rates that take effect July 1, 2025, are as follows:

• Gasoline and compressed natural gas: 48.3 cents per gallon
• Diesel, liquefied natural gas and propane: 55.8 cents per gallon

The Part B Motor Fuel Use Tax Rate that took effect Jan. 1, 2025, will be in effect through Dec. 31, 2025. This part of the tax is determined by taking the average state gas price per gallon and then taking 6.25 percent of that result.

The Part B gas tax rates currently in effect for fiscal year 2025 are as follows:

• Diesel: 19.1 cents per gallon
• Gasoline: 18.6 cents per gallon
• Propane: 17.2 cents per gallon
• Liquefied natural gas: 15.3 cents per gallon
• Compressed natural gas: 12.6 cents per gallon

Parts A and B are combined to determine the effective motor fuel use tax rate.

The increased gas tax comes as Illinois prepares to eliminate its 1 percent grocery tax on Jan. 1, 2026. Despite the statewide law, some municipalities are tapping into their home rule status to keep the 1 percent grocery tax imposed locally.