Illinois IFTA Filing Walkthrough (Quarterly)

Illinois calls IFTA the Motor Fuel Use Tax and runs it out of the Department of Revenue. The Secretary of State handles apportioned plates and the Commerce Commission handles operating authority, so neither one touches your fuel tax account. You register on Form MFUT-12 in MyTax Illinois, you file Form MFUT-15 every quarter, and the sourced fee, deadline, and penalty facts live on the Illinois IFTA page. Here is the order to work through.

Step 1: confirm Illinois is your base jurisdiction

Illinois is your base only when four things are true at once. Your qualified vehicles are registered in Illinois with the Secretary of State. You operate from an established physical place of business in Illinois, which rules out a post office box, a shipping-store address, a virtual office, and an agent's address. Your operational control and operational records sit in Illinois or can be produced there. And the fleet accrues miles on Illinois highways.

A qualified motor vehicle is an interstate vehicle that meets the published axle and weight test, alone or in combination. Stay inside Illinois on fuel bought only in Illinois and you fall into one of the four categories the state exempts from registering. Cross the line a handful of times a year and a single trip permit can beat a license outright; the sourced price, the term, and the penalty for skipping it are on the Illinois trip and fuel permits page.

Step 2: clear the two prerequisites before you apply

Illinois puts two credentials in front of the fuel tax application. Obtaining a U.S. DOT number is a condition of IFTA registration here, which is worth flagging because the Commerce Commission's Public Carrier Certificate, the state's intrastate authority, does not condition the certificate on holding one. Illinois-based commercial motor carriers also file Form REG-1, the Illinois Business Registration Application.

Do both first. The federal number is walked through on the Illinois DOT number page, and the intrastate credential on the Illinois intrastate authority page.

Step 3: apply on Form MFUT-12 in MyTax Illinois

Illinois takes the application electronically through MyTax Illinois. Activate the portal logon before you start, because it uses two-step verification and that is not something to discover the day a deadline lands. The form is MFUT-12, Motor Fuel Use Tax IFTA License and Decals Application.

The license itself costs nothing. Illinois charges per decal set instead, one set for each qualifying vehicle you intend to operate, and both amounts render with sources on the Illinois IFTA page. When the Department requires a bond, it has to equal at least twice the estimated average tax liability of a quarterly return or a statutory floor, whichever is greater, so a heavier expected quarter means a heavier bond.

Step 4: track miles and gallons per jurisdiction all quarter

Each return is built from two running totals per jurisdiction: distance traveled and fuel purchased. ELD or GPS distance records plus fuel receipts are what an auditor reconciles against, and rebuilding three months of them the week a return is due is how carriers end up assessed. The national how to file IFTA guide covers the record set in depth.

Step 5: file Form MFUT-15 by the quarter's due date

Returns are quarterly on Form MFUT-15, due the last day of the month right after the quarter closes: April 30, July 31, October 31, and January 31. A return is due for every quarter once your license and decals issue, even if the trucks never left Illinois or never operated at all. Filing nothing stops being an option the moment you are licensed.

The return applies each member jurisdiction's current rate to your distance and fuel. The Illinois diesel line this quarter is $0.7380IFTA Fuel Tax Rate Matrix, 3rd Quarter 2026 (International Fuel Tax Association, Inc. (IFTA, Inc.))Verified Jul 18, 2026 per gallon in the national matrix. Run the quarter through the IFTA calculator before you submit and compare lines on the IFTA rates by state table. Filing late, filing nothing, or paying short draws a penalty of a flat amount or a share of the delinquent tax, whichever is greater, and the sourced figure renders on the Illinois IFTA page. Interest rides on top of it, set above the federal underpayment rate and reset every January, so no fixed Illinois percentage exists to quote.

Step 6: renew by December 31 and watch the decal grace period

The license and decals run January 1 through December 31. Submit the renewal electronically by December 31 and Illinois gives you a decal display grace period that ends the last day of February, which is room enough to receive the new decals and get them on the trucks. Miss January 1 and there is no grace period at all, and the license status shows as suspended.

That gap is expensive. Running in Illinois without valid decals or a valid single trip permit carries a minimum penalty, with a higher minimum for each later occurrence, sourced on the Illinois trip and fuel permits page. Put the renewal on the calendar in November so the December deadline never sneaks up on you.

FAQ

Who administers IFTA in Illinois?

The Illinois Department of Revenue, which runs it as the Motor Fuel Use Tax. Registration is Form MFUT-12 through MyTax Illinois and the quarterly return is Form MFUT-15.

Do I need a USDOT number before I can get an Illinois IFTA license?

Yes. Illinois makes obtaining a U.S. DOT number a condition of IFTA registration, and Illinois-based commercial motor carriers also file Form REG-1, the Illinois Business Registration Application.

What happens if I renew my Illinois IFTA license late?

You lose the decal display grace period. Renew electronically by December 31 and you have until the last day of February to fit new decals. Renew after January 1 and there is no grace period, and the license status shows as suspended.