More than four months since the first checks were mailed out, the IRS has continued sending out payments from the third stimulus bill. This week, more than two million additional payments were made, including a large number of “plus-up” payments to previous stimulus recipients – bringing the total number of stimulus payments up to around 170 million.

The tax collection agency announced on Wednesday that it had sent an additional 900,000 payments to Americans who had already received a stimulus check, but for which the amount was inaccurate. Because the first stimulus checks were sent in March, and 2020 taxes were not filed until May, many Americans have reported changed circumstances which allowed them to qualify for more stimulus money, necessitating the “plus-up” checks.

For this reason, Americans who filed their taxes in mid-May or later could expect to receive additional payments, depending on their circumstances. For instance, Americans who lost income during the pandemic, putting them below the $75,000 per year cutoff for individuals, can expect to receive a check. Americans who had a child during the pandemic – reported on a family’s 2020 taxes, but not its 2019 ones – can expect to receive an additional $1,400 payment, the amount set aside for dependents.

The remaining 1.3 million new payments are destined for Americans whose information was not in the IRS database before they filed their 2020 tax returns – and therefore never received a stimulus check in March in the first place.

The IRS has been uniquely well-suited to administer the stimulus program. Because it is already accustomed to sending out tax refunds, the process of making payments is routine, and it already receives information on Americans’ incomes during the normal course of its work.

One drawback of using the tax collection agency to make payments, however, has been that the poorest Americans, who do not usually pay any taxes, are often difficult to reach. This is unfortunate because the poorest Americans have the most to gain from stimulus payments, and the payments often do the most good in their hands. This problem is shared between the third round of stimulus checks and the newly-distributed advance Child Tax Credit payments, which are also being administered by the IRS.

The extra workload has also burdened the IRS, which as of early July still needed to process an estimated 35 million tax returns from the most recent filing deadline.

Trevor Filseth is a current and foreign affairs writer for The National Interest.