If you run trucks out of the Metro East, there’s a good chance at least one of them crossed the river into Missouri this week. That one short trip is what pulls a lot of small carriers into IFTA, and the fuel tax return that comes with it lands on your desk four times a year whether you’re ready for it or not.
IFTA, the International Fuel Tax Agreement, lets you report fuel tax for every state you drive in on one quarterly return filed with Illinois. It saves you from registering in Missouri, Indiana, and every other state on your routes, but it only works if your miles and your fuel receipts tell the same story.
The third quarter return is due October 31, so this is a good week to look at how IFTA Illinois works for a carrier and where the paperwork usually goes sideways.
The first question is whether you need a license at all.
Who Has to File IFTA in Illinois?
You need an Illinois IFTA license if your business is based in Illinois and you run a qualified motor vehicle in Illinois and at least one other state. The Illinois Department of Revenue’s IFTA Carrier Compliance Manual (MFUT-53) says the rule applies to any person “based in a member jurisdiction operating a qualified motor vehicle(s) in two or more member jurisdictions.”
A qualified motor vehicle is a truck with two axles and a gross or registered weight over 26,000 pounds, a truck with three or more axles at any weight, or a combination like a tractor and trailer that weighs more than 26,000 pounds together. A pickup towing a light trailer to a job site usually isn’t one, and a day cab pulling a loaded flatbed almost always is.
If you only leave Illinois once or twice a year, you can buy a trip permit from each state you drive into instead of getting an IFTA license. Illinois’s own single-trip permit, for comparison, covers a 96-hour run into or through the state. For a carrier crossing into St. Louis every week, though, the permits add up fast and the license is the simpler path.
Once you have the license, Illinois expects four returns a year on a fixed schedule.
IFTA Returns Are Due Four Times a Year, Even in a Quiet Quarter
Illinois IFTA returns are filed on Form MFUT-15 and are due on the last day of the month after each quarter ends. That works out to April 30, July 31, October 31 and January 31, and the date moves to the next business day if it lands on a weekend or holiday.
The part that catches people is the quiet quarter. MFUT-53 says you must file “even if you had no operations during the quarter,” so a truck that sat in the yard all winter still needs a zero return. Skipping it because nothing happened is one of the easiest ways to end up with a penalty you didn’t need.
Everything runs through MyTax Illinois, including registration, decal orders, the return and the payment. Illinois doesn’t accept paper returns or paper checks for IFTA, so whoever handles your filing needs a login and a habit of using it.
There’s also an annual step. Your license and decals run January through December, and Illinois wants them renewed by December 31 for the coming year. If renewal falls through the cracks, your trucks are technically running without IFTA authority until it’s fixed, which is a bad thing to discover at a scale house.
The return itself is only as good as what you feed into it, which brings us to records.
The Records You Keep Decide How Your Audit Goes
For IFTA, you need a record of every mile and every gallon for each qualified vehicle, and you need to keep it for four years from the date the return was due or filed, whichever is later. That’s the rule in MFUT-53, and it’s where most small fleets have gaps.
On the mileage side, a trip report for each truck should show the dates, where the trip started and ended, the route, the odometer or ECM readings at each end, the total miles, the miles in each state, and the truck’s unit number. A driver jotting “STL and back” on a notepad doesn’t meet that standard, even if it’s accurate.
It may surprise you that your ELD isn’t automatically your IFTA record. Illinois says plainly, “Do not assume your ELD is able to produce the required records necessary to complete your quarterly tax filings.” Some ELDs only hold data for a short time, so if yours is your mileage source, someone needs to export it every month and save it somewhere that will still exist in four years.
Fuel receipts have their own list. Each one needs the date, the seller’s name and address, the gallons, the fuel type, the price, the truck it went into, and the name of the buyer. Handwritten gallons and prices aren’t accepted, and a faded thermal receipt in a glove box isn’t much better.
Those records are what turn into the numbers on your return, so it helps to see how the math actually works.
How the IFTA Return Is Calculated
Your IFTA return figures out how much fuel you burned in each state, compares it to how much you bought there, and settles the difference. You pay the states where you used more than you bought and get credit in the states where you bought more than you used.
Say you run one truck out of Edwardsville. Last quarter it drove 30,000 miles and burned 5,000 gallons, which works out to 6 miles per gallon for the quarter.
Now say 12,000 of those miles were in Illinois. The return treats 2,000 gallons as used in Illinois, and the Illinois fuel you bought at the pump gets credited against that.
Run the same arithmetic for Missouri, Indiana and every other state on the log, and you have your return. MyTax Illinois does the rate lookups and the net balance, and you supply the miles, the gallons and the tax-paid fuel by state.
The miles per gallon figure is the hinge for the whole thing. If your mileage is understated or a stack of receipts never made it into the books, your MPG drifts, and every state’s number on the return drifts with it.
Getting that math wrong is usually what turns a routine filing into an audit problem, and there are a few patterns we see again and again.
Common IFTA Mistakes and What Triggers an Audit
The most expensive mistake is not having records when an auditor asks for them. MFUT-53 says that if you can’t produce records on demand, “the auditor may use a standard of four miles per gallon and issue an assessment.” For most diesel trucks, four miles per gallon is a lot worse than reality, and the tax bill follows.
If your records aren’t adequate, the auditor can cut your reported fuel economy by 20%, or drop it to 4.00 MPG, and disallow any tax-paid fuel that isn’t backed by a proper receipt. In an IFTA audit, the burden sits with the carrier to show the return was right.
The other mistakes we see are quieter:
1. Filing late. Illinois sets the penalty at $50 or 10% of the tax owed, whichever is greater, plus IFTA interest at two points above the IRS underpayment rate.
2. Skipping zero returns for parked trucks or slow quarters.
3. Fuel bought on a personal card, or for a truck that isn’t listed, that never gets matched to the right unit.
4. ELD data that gets overwritten before anyone saves it.
5. Decals moved from a sold truck to a new one, which Illinois doesn’t allow.
Most of these come down to the same thing, which is that the miles and fuel only get looked at once a quarter, a few days before the deadline.
Monthly Bookkeeping Makes IFTA a Lot Less Painful
The carriers who have an easy time with IFTA are the ones whose books reconcile miles and fuel every month. When fuel card statements, receipts, and trip reports are matched to each truck as they come in, the quarterly return is mostly a matter of adding up three months that are already done.
That’s how we approach accounting for trucking companies. We tie fuel and miles out by unit every month, flag receipts that are missing details while the driver still remembers the stop, and keep the four-year record set in one place so an audit letter doesn’t send anyone digging through cabs.
It also helps outside of IFTA. Clean monthly bookkeeping gives you a real cost per mile, a clear view of cash between fuel day and freight payment, and better numbers when it’s time to think about equipment purchases and the rest of your business tax planning.
A lot of Metro East carriers are family businesses, and some of those families have a kid away at college. When that’s you, your business return and your student’s return don’t really get filed in isolation. We walk through how to line them up in our post on family tax coordination with college students.
Do You Need a CPA to File IFTA?
You don’t need a CPA to file IFTA. Plenty of owner-operators file their own returns in MyTax Illinois, and software can handle the state-by-state math.
Where it pays to have help is when the records aren’t clean, when the fleet is growing past what one person can track, or when an audit notice shows up. Illinois sends a Notice of Audit Initiation before an audit starts, and that letter usually gives you about 30 days’ notice. That window is much more comfortable when someone already knows where every receipt is.
This is general information about Illinois IFTA filing, and your situation depends on your vehicles, your routes and your records.
If you liked this one, you’ll probably also like our post on quarterly estimated taxes for Illinois self-employed owners.
If your next IFTA return is due and the receipts are still in a shoebox, reach out to Thompson Flaherty, and we’ll help you get the quarter reconciled and filed.
Until next time!
