The Illinois fuel tax is 48.3 cents per gallon on gasoline and gasohol and 55.8 cents per gallon on diesel through June 30, 2026, with both rates rising on July 1. Those state per-gallon rates are only part of what you pay at the pump: a 1.1-cent Underground Storage Tank charge, a prepaid sales tax of roughly 17 cents per gallon, and the federal excise tax of 18.3 cents on gasoline or 24.3 cents on diesel all stack on top. Electric vehicle owners skip the pump but pay a $100 annual surcharge built into their registration. Commercial interstate carriers have their own system under IFTA.
Current Per-Gallon Rates
For the fiscal year ending June 30, 2026, Illinois charges 48.3 cents per gallon on gasoline and gasohol and 55.8 cents per gallon on diesel. On July 1, 2026, gasoline rises to 49.6 cents and diesel rises to 57.1 cents.1Illinois Department of Revenue. FY 2026-23, Change in the Motor Fuel Tax Rate, Effective July 1, 2026, Through June 30, 2027
The rate adjusts every July 1. Under 35 ILCS 505/2, the Department of Revenue ties the increase to the average Consumer Price Index for the 12 months ending in March and rounds to the nearest tenth of a cent. Diesel carries the higher rate because of a 7.5-cent-per-gallon surcharge added in 2019.2Illinois General Assembly. Illinois Compiled Statutes 35 ILCS 505/2 – Motor Fuel Tax Law
Alternative Fuels
Compressed natural gas, liquefied natural gas, and liquefied petroleum gas are taxed by energy equivalent rather than liquid gallon. Starting July 1, 2026, CNG is taxed at 49.6 cents per gasoline gallon equivalent (5.66 pounds), and LNG and LPG are taxed at 57.1 cents per diesel gallon equivalent (6.06 pounds for LNG, 6.41 pounds for LPG).1Illinois Department of Revenue. FY 2026-23, Change in the Motor Fuel Tax Rate, Effective July 1, 2026, Through June 30, 2027
What Else Is Baked Into the Pump Price
The state motor fuel tax is the largest single charge, but it isn’t the only one. Three other taxes apply to every gallon sold in Illinois.
Underground Storage Tank Tax and Environmental Impact Fee
Every gallon of petroleum product received in Illinois carries a combined 1.1 cents in extra charges: 0.3 cents for the Underground Storage Tank tax and 0.8 cents for the Environmental Impact Fee.3Illinois Environmental Protection Agency. Illinois Underground Storage Tank Fund Guide These fund the cleanup of contaminated underground tank sites. They apply to gasoline, diesel, home heating oil, and kerosene, and the whoever first sells or uses the fuel in Illinois (the “receiver”) owes them.4Illinois Department of Revenue. Motor Fuel Tax General Overview
Prepaid Sales Tax
Illinois also collects a flat prepaid sales tax at the distributor level. For the first half of 2026, that comes to 17 cents per gallon for most gasoline and diesel, 15 cents for E15 gasohol, and 13 cents for mid-range ethanol blends. Fuel that is majority ethanol, or qualifying biodiesel, is exempt.5Illinois Department of Revenue. Prepaid Sales Tax Rates
Federal Excise Tax
The federal government adds 18.3 cents per gallon on gasoline and 24.3 cents on diesel.6U.S. Energy Information Administration. How Much Tax Do We Pay on a Gallon of Gasoline and on a Gallon of Diesel Fuel Combine everything, and a gallon of regular gasoline in the first half of 2026 carries roughly 84 cents in fixed per-gallon taxes before any local sales tax is calculated on the sale.
Electric Vehicle Surcharge
Fully electric vehicles pay no fuel tax, so Illinois collects a $100 annual surcharge on top of the standard $151 passenger registration fee. Total annual registration for an EV comes to $251, and the surcharge is deposited into the Road Fund to partially offset the fuel tax revenue the vehicle would otherwise generate.7Illinois Secretary of State. Electric Vehicle License Plates A gasoline car driven 12,000 miles a year at 30 miles per gallon pays roughly $193 in state motor fuel tax, so the $100 figure doesn’t fully close the gap.
IFTA Rules for Commercial Carriers
If you run qualifying heavy vehicles across state lines, you register under the International Fuel Tax Agreement rather than paying Illinois motor fuel tax at the pump. A qualifying vehicle meets any of these criteria:
- Two axles with a gross or registered weight over 26,000 pounds
- Three or more axles regardless of weight
- A combination vehicle with combined weight over 26,000 pounds
IFTA registration costs nothing for the license itself; decals run $3.75 per vehicle, and you get two per truck. Both are valid from January 1 through December 31.8Illinois Department of Revenue. Illinois Motor Fuel Use Tax IFTA License and Registration Properly displayed decals let you travel through member jurisdictions without buying individual trip permits. Operating without them is expensive: a first offense means a traffic citation and a minimum $1,000 penalty, and a second offense doubles the floor to $2,000.9Illinois Department of Revenue. Motor Fuel Tax Fraud/Violations
Carriers that aren’t IFTA-registered can buy a 96-hour fuel trip permit before entering Illinois. You have to purchase it before you cross the state line; Illinois does not let you enter for the purpose of obtaining one.
Filing Deadlines
Everyday drivers never file a motor fuel tax return. The tax is built into the price and collected further up the chain by licensed distributors, who hand it over to the Department of Revenue.4Illinois Department of Revenue. Motor Fuel Tax General Overview If you are a distributor, a receiver, or an IFTA carrier, you file through MyTax Illinois on this schedule:
- Distributors file Form RMFT-5 monthly, due by the 20th of the following month. Returns are required even when there were no transactions.10Illinois Department of Revenue. RMFT-5, Motor Fuel Distributor Tax Return Instructions
- Receivers file Form RMFT-5-US monthly for the UST tax and Environmental Impact Fee, also by the 20th, even when all purchases were tax-paid.11Illinois Department of Revenue. RMFT-5-US MyTax Illinois Filing Instructions
- IFTA carriers file Form MFUT-15 quarterly, due by the last day of the month following each quarter: April 30, July 31, October 31, and January 31.12Illinois Department of Revenue. Illinois Motor Fuel Use Tax IFTA Filing and Payment Requirements
IFTA returns report total miles driven and fuel purchased in every jurisdiction, and the system calculates whether you owe more or are entitled to a credit for taxes overpaid elsewhere. Keep all supporting records (receipts, mileage logs, fuel purchase records) for at least four years from the filing date or due date, whichever is later.12Illinois Department of Revenue. Illinois Motor Fuel Use Tax IFTA Filing and Payment Requirements
Penalties and Interest
Illinois charges separate penalties for filing late and paying late, and they get steeper the longer you wait. For most motor fuel taxes:
- Late filing: the lesser of $250 or 2% of the tax due. If you still haven’t filed within 30 days of a nonfiling notice, the penalty becomes the greater of $250 or 2% of the tax shown due, capped at $5,000.
- Late payment, 1 to 30 days: 2% of the unpaid tax.
- Late payment, 31 days or more: 10% of the unpaid tax.
- Discovered after an audit starts: 15% of any amount not paid until the Department initiates an audit, rising to 20% if still unpaid 30 days after the audit concludes.
IFTA carriers face a flat schedule: 10% of the tax due or $50, whichever is greater.13Illinois Department of Revenue. Pub-103, Penalties and Interest for Illinois Taxes Interest accrues on top. For IFTA balances in 2026, the annual interest rate is 9%, calculated at 0.75% per month, set at two percentage points above the IRS underpayment rate.14Illinois Department of Revenue. IFTA Interest Rates
Refunds for Off-Road Use
If you paid motor fuel tax on gasoline that never touched a public road (farm tractors, construction equipment, landscaping machinery, and similar uses), you can claim a refund. File Form RMFT-11-A, or submit electronically through MyTax Illinois if you have a motor fuel refund account.15Illinois Department of Revenue. Motor Fuel Refunds
A few things to know before you file. The Department rejects claims that use estimated or rounded figures for miles, gallons, or hours; you need exact records. Farmers should use dyed diesel in tractors, which is already exempt, rather than claiming refunds on undyed diesel. Dyed diesel is not eligible for a refund at all because it was never taxed in the first place.15Illinois Department of Revenue. Motor Fuel Refunds
Deadlines depend on your status. Licensed motor fuel distributors have one year from the date the tax was paid. Everyone else has two years.15Illinois Department of Revenue. Motor Fuel Refunds
Disputing an Assessment
If the Department sends you a Notice of Tax Liability, Notice of Deficiency, or similar assessment and you think it’s wrong, you generally have 60 days from the notice date to respond. IFTA assessments give you only 30 days. Your options depend on the amount at stake:16Illinois Department of Revenue. Your Options to Dispute Illinois Department of Revenue Deficiencies, Assessments, or Claim Denials
- Independent Tax Tribunal: required when the disputed tax (excluding penalties and interest) exceeds $15,000, or when penalties and interest alone exceed $15,000 with no underlying tax.
- Administrative hearing: for disputes below the Tribunal threshold. Motor fuel tax protests use Form AH-4.
- Payment under protest: pay the full amount and file Form RR-374 to preserve your right to challenge it in circuit court. Not available for claim denials.
- Board of Appeals: for requesting penalty and interest waivers based on reasonable cause, or proposing an offer in compromise if you can’t afford to pay.