IFTA Tax Rates in Illinois (2026)

Key numbers at a glance

Illinois is the freight crossroads of the Midwest — I-80, I-90, I-55 and I-70 all pour through Chicagoland — so almost every interstate carrier burns Illinois gallons every quarter. The state is also one of the few whose IFTA rate includes a sales-tax-equivalent piece, which is why its numbers tower over Wisconsin and Missouri next door. The Tax Foundation's July 2026 ranking puts Illinois second nationally in combined gasoline tax at roughly 70.4 cents once every fee is counted.

The rate arrives in two pieces, and understanding the split is what keeps your filings honest. Part A is the classic excise tax, set each July 1 with the Consumer Price Index. Part B is Illinois's replacement for charging sales tax on fuel: each January 1 the Department of Revenue applies 6.25 percent to the average selling price of the previous twelve months and converts it to cents per gallon. For IFTA purposes you simply report the combined figure. The full national picture, including Illinois's neighbors, is on our IFTA rates by state hub.

IFTA tax rates in Illinois

Per Illinois Department of Revenue Informational Bulletin FY 2026-24-A, the motor fuel use tax rates for interstate carriers run July 1 through December 31, 2026. Rates as of Q4 2026 — confirm the current official IFTA matrix before filing.

One 2026 quirk worth knowing: Public Act 104-0468, signed June 16, 2026, suspended the scheduled July 1, 2026 CPI adjustment to Part A for six months. That is why the 55.8-cent diesel and 48.3-cent gasoline Part A rates carried over from the prior year instead of stepping up — and why the bulletin was reissued mid-year. Part B rates were set January 1, 2026 and hold through December 31. DGE means diesel gallon equivalent and GGE gasoline gallon equivalent.

Fueling strategy: Illinois versus its neighbors

The diesel-rate spread around Illinois is the widest of any Midwest border. Neighbor figures below come from the current IFTA matrix (as of Q4 2026 — confirm the current official IFTA matrix; Kentucky's figure includes its use-tax line).

The math is blunt: Illinois diesel costs 44.3 cents a gallon more than Missouri's on paper. Filling 120 gallons in Missouri instead of Illinois prepayes roughly $53 of tax you were going to owe on Illinois miles anyway — money that otherwise shows up as a balance due on your MFUT-15 quarterly return. Around Chicagoland, fueling in Indiana (63.0-cent diesel) still beats Illinois by nearly 11 cents, though it loses to every other border state. The usual caveat applies: compare pump price minus tax, because a cheap-looking Illinois pump already carries the 73.8 cents inside it, and chasing marginal stops adds out-of-route miles that cost more than they save — our deadhead miles guide covers that trade. Model your exact route in the IFTA calculator.

How Illinois IFTA affects your filings

Illinois-based carriers file the quarterly return with the Illinois Department of Revenue through MyTax Illinois; pass-through carriers simply carry Illinois lines on their home-state return. The formula is unchanged: taxable gallons equal Illinois miles divided by truck MPG, times the combined rate. Drive 300 Illinois miles at 6.5 MPG and you burn 46.2 gallons — 46.2 times $0.738 is $34.06 of Illinois fuel tax for that slice alone. Do it for every jurisdiction, subtract the tax already embedded in your pump receipts, and the sum is your net due or refund.

Because Illinois resets rates twice a year — Part B each January 1, Part A each July 1 absent a suspension — pull a fresh matrix every quarter rather than reusing the last one. Deadlines are April 30, July 31, October 31 and January 31, with late penalties typically $50 to $100 plus interest. Auditors in Illinois, like everywhere, ask for four consecutive quarters of receipts, per-state distance records (ELD or GPS), and your MPG calculation; mismatched receipts and miles remain the number one finding. Carriers who buy most fuel outside Illinois should expect a recurring balance-due line and budget for it quarterly instead of being surprised in January.