The so-called "plus-up" payments will be sent to taxpayers who didn't receive as much money as they were entitled to in the third round of cash payments authorized by Congress last month.
The $1,400 checks were calculated based on an individual's 2019 or 2020 tax return. But those returns didn't always accurately capture a person's financial situation; for instance, millions of Americans who lost their jobs, or saw their income reduced, last year as a result of the pandemic were actually qualified for a bigger check. That also includes individuals who had a child in 2020.
The agency estimated that it will send about $1.2 billion in additional payments.
If you already received your third stimulus check but are owed more based on your 2020 tax returns, the agency will automatically adjust the payment after you file your returns with a "plus-up" check.
The first wave of plus-up payments went out earlier this month; the IRS committed to delivering them on a rolling basis to everyone who is eligible as it continues to process 2020 returns.
Still, the IRS cautioned people last week that some payments may be worth less than expected, depending on several factors. The agency said it would send a letter explaining any discrepancies, but noted it could cause a "slight delay in processing the return."
One issue may arise from dependents and the differing rules on who's qualified for the money.
The first round of stimulus checks, for instance, provided $500 for dependents under the age of 17. The second check offered $600 for children under the age of 17, and the third check – the largest – gave $1,400 for all dependents, regardless of age.
But some Americans may mistakenly claim an extra $500 or $600 from the first two checks on their tax return, even though their child turned 17 on Jan. 1, 2020, and is not actually eligible for the money.
Another mix-up may stem from divorced parents if both parents try to claim the same dependent on their taxes. Only the parent who claims the child as a dependent should get the stimulus check adjustment, according to the tax website 1040.com.
The IRS has so far delivered 159 million stimulus checks worth more than $376 billion.
You can check the status of your payment using the IRS’s Get My Payment tool.