The Internal Revenue Service (IRS) hopes that the estimated 1 million taxpayers due a refund for the 2013 tax year will file their delinquent returns by April 18, 2017 – the deadline for them to claim their share of more than $1 billion in potential refunds. In California alone, an estimated 97,200 taxpayers may be able to claim over $93 million, with a median expected individual refund of $696.

“Their window of opportunity is closing soon,” said IRS Commissioner John Koskinen. “Students and many others may not realize they’re due a tax refund. Remember, there’s no penalty for filing a late return if you’re due a refund.”

However, if the taxpayer owed a refund for 2013 has not yet filed for 2014 or 2015, the refund check may be held to offset potential amounts still owed to the IRS, a state tax agency, or for unpaid child support or past-due federal debts (such as student loans).

Read the full IRS press release, including details on where to find year 2013 tax forms, here.