(WJW) — The Internal Revenue Service says it has more than $1.3 billion in unclaimed tax refunds for an estimated 1.3 million people.

The unclaimed refunds are for people who did not file a 2017 Form 1040 federal income tax return. The window to file the 2017 returns is May 17.

“The IRS wants to help taxpayers who are due refunds but haven’t filed their 2017 tax returns yet,” IRS Commissioner Chuck Rettig said in a news release.

“Time is quickly running out for these taxpayers. There’s only a three-year window to claim these refunds, and the window closes on May 17,” he said. “We want to help people get these refunds, but they will need to quickly file a 2017 tax return.”

See a breakdown of the median potential refund for each state here.

By not filing a tax return, people could lose more than just their refund of taxes withheld or paid during 2017. Many low and moderate-income workers may be eligible for the Earned Income Tax Credit.

Current and prior year tax forms (such as the tax year 2017 Form 1040, 1040-A and 1040-EZ) and instructions are available on the IRS.gov Forms and Publications page or by calling toll-free 800-TAX-FORM (800-829-3676). Taxpayers who are missing Forms W-2, 1098, 1099 or 5498 for the years 2017, 2018 or 2019 should request copies from their employer, bank or other payer.