Is Your Fleet Overpaying Federal Fuel Excise Tax? A New Lawsuit Puts (Reefer) Fuel Back in the Spotlight
If your business runs refrigerated trailers, a lawsuit filed last month in Missouri federal court is worth your attention — even if your fleet is a fraction the size of the carrier that filed it.
The Case
In June 2026, Prime Inc., one of the country’s largest refrigerated trucking companies, sued the IRS in the U.S. District Court for the Western District of Missouri seeking a refund of more than $11 million in federal fuel excise tax. The tax at issue wasn’t paid on the diesel that moves Prime’s trucks down the highway. It was paid on diesel burned by the refrigeration units — “reefers” — mounted on Prime’s trailers to keep cargo cold.
Prime’s position is straightforward: fuel used to run a refrigeration unit doesn’t propel a vehicle on the highway. It runs a separate motor that happens to be bolted to a trailer. Under the federal fuel tax rules, diesel used for a business purpose other than highway propulsion generally qualifies as an “off-highway business use” — and off-highway use isn’t supposed to be taxed at the highway rate in the first place, or is refundable if it was.
Prime says it structured its fuel purchases specifically to support that position: reefer fuel is bought on a separate company fuel card, tracked apart from tractor fuel, and burned in a physically distinct fuel system. The company sought refunds administratively for several years running, the IRS turned those claims down, and Prime has now taken the fight to federal court.
Why This Isn’t Just a “Big Fleet” Issue
The fuel tax credit Prime is litigating over isn’t some exotic, custom-built tax position available only to fleets with in-house legal departments. It’s a standard federal fuel tax credit — the same credit available to a five-truck reefer operation, a produce hauler, a cold-storage logistics company, or any business that burns taxed diesel for a purpose other than moving a vehicle down a public road. Farm equipment, off-road construction equipment, and stationary generators have claimed versions of this credit for years. Refrigerated trailer units sit squarely in that same family of arguments.
If your business pays fuel excise tax on diesel that goes into a reefer unit rather than a truck engine, the question Prime is asking the court is the same question you should be asking your tax advisor: are you leaving a refundable credit on the table?
How the Credit Actually Works
There are a few practical paths to recovering this money, and they’re not identical:
- Form 4136 (Credit for Federal Tax Paid on Fuels) lets you claim the credit against your income tax when you file your annual return. It’s the slowest of the options, but the most commonly used.
- Quarterly claims through the appropriate excise tax forms can get money back faster if your nontaxable fuel use is large enough to meet the dollar thresholds.
- Amended or protective refund claims can be filed for open years while a case like Prime’s works its way through the courts, preserving your ability to benefit from a favorable outcome without waiting for the litigation to conclude.
None of these are automatic. The IRS doesn’t proactively identify overpayments and cut a check — the taxpayer has to make the claim, and the claim has to be documented well enough to survive scrutiny.
The Piece That Actually Decides These Cases
Here’s the detail that matters most, and it’s the same detail we’d flag for any client considering this credit: the legal theory is not usually where these disputes are won or lost. The IRS has long conceded, in one form or another, that genuinely off-highway fuel is not subject to the highway tax rate. Where these cases get contested is proof.
If reefer fuel and tractor fuel come out of the same tank, get purchased on the same card, or can’t be cleanly separated in your records, the IRS’s default position is that all of it was used in a highway vehicle — full stop. That’s why Prime’s complaint spends so much time on how its fuel purchasing is structured: separate tanks, separate fuel cards, and (implicitly) a paper trail built to show exactly how many gallons went where.
Any business considering this credit would greatly benefit from that same kind of separation and recordkeeping before filing a refund claim; not after.
What We’re Watching, and What You Should Do Now
This case is in its early stages, and it will likely take a year or more to resolve. A win for Prime wouldn’t create new law so much as it would reinforce a position the IRS has resisted paying out on. A loss would sharpen exactly what documentation the agency expects to see.
Either way, the underlying credit already exists today — you don’t need to wait for a court decision to evaluate whether your fleet has been overpaying. If your business burns diesel in refrigeration units, auxiliary power units, or other off-highway equipment mounted on or used alongside your vehicles, now is a good time to:
- Review how that fuel is purchased and tracked
- Determine whether prior tax periods are still open for a refund claim
- Talk to your tax advisor about whether a protective claim makes sense while this litigation plays out
We’re following this case closely. If you have questions about whether your business may be entitled to a fuel tax refund, please contact Josh O. Ungerman at his direct dial at (214)749-2427 or email jungerman@meadowscollier.com.