The IRS said last month that it was sending letters to more than 9 million individuals and families who have not yet filed an income tax return but are eligible for several important tax credits they missed out on in 2021. Some of these may be worth thousands of dollars. They include the child tax credit (temporarily expanded to up to $3,600 per eligible child in 2021); the recovery rebate credit (worth as much as $1,400 per person); the earned income tax credit (as much as $6,728 depending on your family situation.); and others. Many tax credits were boosted significantly in 2021 as part of the government’s response to the COVID-19 pandemic, but some potential recipients of the aid did not know about the credits or how to claim them—partly because some became available to people whose income  is so low they don’t normally file income taxes. The good news for late filers is that credits can be claimed up to three years after they were due. That means you have until April 2025 to file your 2021 taxes and claim credits that you may have overlooked. There’s no late fee for filing your taxes late if you are owed a refund.  The IRS is also keeping its Free File system open through Thursday, November 17 to give qualifying latecomers a last chance to file their taxes online without paying a fee to a tax prep company. Free File is tax software for people whose adjusted gross income is $73,000 or less. The system also provides electronic tax forms for taxpayers at any income level.  Correction - Nov. 14, 2022: This article has been updated to correct the date that the IRS sent out letters to taxpayers with unclaimed tax credits. Have a question, comment, or story to share? You can reach Diccon at dhyatt@thebalance.com.