File for it, or lose it forever.

July 10 is the drop-dead deadline for tens of millions of Americans to file for a potential COVID-related IRS refund. If taxpayers haven’t filed with the IRS by then to protect a potential refund or abatement, they will lose that chance forever.

The potential tax refund stems from a federal judge’s ruling in Kwong v. United States late last year suggesting the federal tax filing and payment deadlines were automatically suspended during the federally declared COVID-19 disaster period from January 20, 2020, through May 11, 2023. The government is appealing the ruling, but if the decision stands, millions of Americans who paid or were charged late fees or interest during those 3.5 years may be due a refund since everything was on hold.

But here’s the catch: Americans can’t wait for the outcome of the litigation to file for a refund or abatement. The law puts a deadline on how long people get to claim the refund, and that formula brings the last day to do so to July 10, 2026, tax experts said. The IRS hasn’t advertised this because it likely would rather not have to refund potentially billions of dollars to individuals, businesses and trusts and estates, but lawyers, accountants and the independent National Taxpayer Advocate have been trying to spread the word for months.

“Time is critical for people considering filing a claim,” said Glen Frost, Frost Law’s founding partner.

How to Know If You Qualify — and How to File

Independent National Taxpayer Advocate (NTA) Erin Collins, as well as law firms and accountants, have published guidelines and steps for Americans to take to figure this out.

To make things simpler, some firms had created quick and simple tools to help. But since the deadline is now so close, some have closed. Frost Law said it helped hundreds of taxpayers with its tool before closing it on June 24.

Website covidtaxrefunds.com remains open and has received thousands of requests so far, according to Alyssa Maloof Whatley with EasAlyAI and Frost Law.

But some lawyers warned this window may also close soon due to the nearing deadline. If a taxpayer needs help from someone like a return preparer or another third party who needs to access the taxpayer’s information to support a Kwong claim, the IRS requires an authorization form (IRS Form 8821). These typically take 14 days to clear the IRS.

That doesn’t mean taxpayers can’t still file a claim on their own. NTA has details on steps people can take.

A taxpayer may file their claim using IRS Form 843, claim for refund and request for abatement, using information from their tax transcript found online, said Jon Wasser, partner at Fox Rothschild who focuses on tax issues.

In most cases, taxpayers should file a separate Form 843 for each tax period and type of tax, Collins said.

A taxpayer should specify on the form that it’s a protective claim based on the Kwong v. United States decision regarding Section 7508A(d) and the COVID-19 disaster period, lawyers said.

“You’re basically telling the IRS, ‘Here’s a refund claim, put it on hold for now,’” until the case has a final determination, Wasser said. If after all litigation is complete, the IRS must issue refunds, then you would have preserved your right to claim yours.

Since the deadline is firm, and July 10 is so close, “mail it (your claim) in by certified mail before July 10,” Frost said. “The certified mail option ensures there’s no question the Kwong claim reached the IRS before the July 10 deadline.”

Medora Lee is a money, markets, and personal finance reporter at USA TODAY. You can reach her at [email protected] and subscribe to our free Daily Money newsletter for personal finance tips and business news every Monday through Friday.