The Illinois gas tax varies by county because local governments stack their own per-gallon charges on top of the state’s. Every driver in the state pays a 48.3-cent state excise tax on gasoline (55.8 cents on diesel), a 6.25% state sales tax, a 0.3-cent underground storage tank fee, and the 18.3-cent federal excise tax.1Illinois Department of Revenue. FY 2025-23, Change in the Motor Fuel Tax Rate2Illinois Department of Revenue. Motor Fuel Tax Rates and Fees3U.S. Energy Information Administration. How Much Tax Do We Pay on a Gallon of Gasoline and Diesel Fuel? Where you fill up decides what gets added on top. In Chicago, the pump price includes an additional Cook County fuel tax and an 8-cent city fuel tax; in the collar counties, a county tax of 4 to 8 cents applies; in most downstate counties, nothing extra beyond the state and federal layers. Total tax burden can run past 80 cents per gallon in the highest-tax locations.
What Every Illinois Driver Pays
The state excise tax is the biggest single line. For July 1, 2025 through June 30, 2026, it sits at 48.3 cents per gallon on gasoline and 55.8 cents on diesel.1Illinois Department of Revenue. FY 2025-23, Change in the Motor Fuel Tax Rate That rate has roughly doubled since 2019, when the state charged 19 cents per gallon.
On top of the excise tax, Illinois applies its 6.25% state sales tax at the pump. Because it’s a percentage, the sales tax rises with gas prices; at $4.00 per gallon before taxes, it adds roughly 25 cents. A 0.3-cent-per-gallon underground storage tank fee applies statewide to fund cleanup of contaminated fuel storage sites.2Illinois Department of Revenue. Motor Fuel Tax Rates and Fees The federal government adds 18.3 cents per gallon of gasoline, a rate unchanged since 1993.3U.S. Energy Information Administration. How Much Tax Do We Pay on a Gallon of Gasoline and Diesel Fuel?
Those charges apply to every gallon sold in Illinois. County and municipal taxes are what create the geographic variation.
County Fuel Taxes
The Collar Counties
DuPage, Kane, Lake, McHenry, and Will counties are each authorized under the County Motor Fuel Tax Law to charge between 4 and 8 cents per gallon.4Illinois General Assembly. Illinois Compiled Statutes 55 ILCS 5 – Counties Code These county rates adjust annually each July 1 based on the Consumer Price Index, capped at a one-cent increase per year. The revenue must be spent on road construction, maintenance, and right-of-way acquisition within the county that collected it. Kane County has statutory authority to exempt diesel from its county tax.
Cook County
Cook County levies its own gasoline and diesel fuel tax under a separate county ordinance, which the county board amended in December 2023.5Cook County Government. Gasoline and Diesel Fuel Tax Check the county’s current schedule directly for the exact per-gallon amount, since it has moved by ordinance rather than by the automatic statewide indexing formula.
Other Counties
Counties outside those listed above don’t have general statutory authority to impose their own per-gallon fuel tax on retail sales. If you fill up in most downstate counties, your total tax is the state and federal layers only.
Municipal Fuel Taxes
Municipal authority to tax fuel is narrow. Only cities and villages inside Cook County (the only Illinois county with more than 3 million residents) can add a motor fuel tax of up to 3 cents per gallon on retail sales, in one-cent increments.6Illinois General Assembly. Illinois Compiled Statutes 65 ILCS 5/8-11-2.3 – Municipal Motor Fuel Tax Law Municipalities elsewhere in Illinois do not have that same statutory power.
Chicago goes further. The city imposes its own vehicle fuel tax of 8 cents per gallon, separate from both the state and Cook County taxes.7City of Chicago. Vehicle Fuel Tax (7577) A gallon bought in Chicago therefore carries the federal excise tax, the state excise tax, the state sales tax, the UST fee, the Cook County fuel tax, and the city’s 8-cent fuel tax. That stacking is why Chicago consistently ranks among the most expensive places to buy gas in the Midwest.
Why the Rate Keeps Climbing
The state excise tax isn’t a fixed number. Every July 1, it goes up automatically by the percentage change in the Consumer Price Index for All Urban Consumers over the prior 12 months ending in March, rounded to the nearest tenth of a cent.8Illinois General Assembly. Illinois House Bill 4211 – 104th General Assembly The rate never drops in a low-inflation year; it holds and waits for the next increase.
The 2019 Rebuild Illinois plan doubled the state motor fuel tax from 19 cents to 38 cents per gallon effective July 1, 2019, and built the annual CPI adjustment into the statute.9State of Illinois. Gov. Pritzker Signs Historic Bipartisan $45 Billion Rebuild Illinois Capital Plan Every year since, the rate has ticked up without a new vote. The collar-county rates ratchet up the same way under their own one-cent annual cap.
The federal 18.3-cent rate is not indexed to inflation, so its share of your total tax bill has shrunk in real terms over three decades while the state and county shares have grown.
What Electric Vehicle Drivers Pay Instead
Drivers who never buy gasoline don’t escape the road-funding system. Illinois charges an additional annual registration fee of $100 on electric vehicles on top of the standard registration charge, bringing the total annual renewal to $251.10Illinois Secretary of State. Electric Vehicle License Plates The extra $100 goes directly into the Road Fund as a substitute for the motor fuel tax the vehicle would otherwise generate.
For a rough comparison: a driver covering 12,000 miles per year in a car averaging 25 miles per gallon pays roughly $232 annually in state motor fuel excise tax alone at the current 48.3-cent rate. The $100 EV surcharge recovers less than half of that. That gap doesn’t include any county or city fuel taxes the same driver would also have paid at the pump.
Estimating Your Own Per-Gallon Tax
To work out roughly what you’re paying in taxes on a gallon of gasoline in Illinois, add:
- 18.3 cents federal excise tax
- 48.3 cents state excise tax (55.8 cents for diesel)
- 0.3 cents state underground storage tank fee
- 6.25% of the pre-tax retail price as state sales tax
- The county fuel tax, if you’re in one of the collar counties or Cook County
- The municipal fuel tax, if you’re in a Cook County city that imposes one (8 cents in Chicago)
Downstate, that math typically stops after the state and federal lines. In the Chicago area, all six lines apply, which is why the same gallon that costs one price in a downstate county costs meaningfully more inside city limits.