A recent audit of child tax credit payments – a provision of the American Rescue Plan passed amid the COVID-19 pandemic – showed the IRS delivered the overwhelming majority correctly.

The small margin of error, however, represents a massive number, with some $3.7 billion is still owed to eligible taxpayers.

The audit, conducted by the Treasury Inspector General for Tax Administration,  reviewed the Internal Revenue Service’s handling of the expanded child tax credit. The expansion increased the credit from $2,000 to $3,600 for each child younger than age 6 and $3,000 for children under age 18. Half of the total – $1,800 or $1,500 – was payable in six monthly installments of $300 or $250 starting July 2021, with the rest refundable with tax returns.

The payments were made July through December 2021 but efforts to extend them into 2022 failed.

The audit reviewed 178.9 million child tax credit payments made between July and November 2021, totaling more than $76.7 billion. Of those, 175.6 million totaling about $75.6 billion were distributed correctly. However, 3.3 million payments worth more than $1.1 billion were sent to 1.5 million taxpayers who did not qualify. Also, the IRS did not send 8.3 million payments worth about $3.7 billion to 4.1 million eligible taxpayers.

The review also identified 11.459 payments worth $4.2 million that were erroneously sent to 523 bank accounts and incorrect updates to direct deposit information for 1,610 taxpayers with bank account information associated with things like health savings accounts.

What to do if you didn’t receive your child tax credit

If you have a child and did not receive the child tax credit, the first thing you should do is determine if you are eligible. To qualify for the full amount, your adjusted gross income must be below $75,000 as a single filer or $150,000 for married couples filing jointly. Single filers with income up to $200,000 or married joint filers with income up to $400,000 are eligible for partial refunds.

If you have a qualifying income you may still be able to claim the credit by filing a 2021 tax return, even if you aren’t typically required to do so. People requesting an extension on filing have until Oct. 17 to submit their information. If you didn’t file for an extension, there is no penalty for late filing if you don’t owe money.

You can go here for information on filing a return and more on child tax credits.