The IRS is continuing to distribute third-round stimulus payments worth up to $1,400 to eligible Americans. The agency recently announced the distribution of its ninth batch of such payments, bringing the total number sent out to American households to over 165 million with a total value of more than $388 billion.

Those Americans who have not received stimulus payments, but who still believe are eligible for one, likely fall into one of two categories.

Eligibility for the third round of direct federal stimulus payments was initially made based on information contained in 2019 tax returns, which at the time represented the most recent data available to the IRS. In order to be eligible for a full $1,400 payment, individuals must have an adjusted gross income (AGI) of no more than $75,000. This number increases to $112,500 and $150,000 for heads of households and couples filing jointly, respectively. In addition, individuals with an AGI of up to $80,000 are eligible for a reduced payment, as are heads of households and couples filing jointly with AGIs of up to $120,000 and $160,000, respectively.

The IRS began the process of distributing payments based on the above criteria using 2019 tax returns, but for many Americans 2020 was a particularly difficult year. For this reason, the IRS has been sending additional money to some people through what it calls “plus-up” payments. These supplemental payments are designed for those people whose initial eligibility was determined by their 2019 tax returns, but whose 2020 returns indicated a loss of income or change in dependent status that entitled them to more money.

The other major category of people who may not have received a stimulus payment yet despite qualifying for one are those people about whom the IRS did not have sufficient information, including those people who did not file a 2019 tax return.

The good news for the people who fall into either one of these categories is that the IRS is actively working to ensure that payments are sent out to them. The most recent batches of stimulus payments distributed to Americans were primarily focused on those people whose eligibility for payments was dependent on the processing of tax returns. Those who have not yet received their payments, or who fall into one of the income brackets described above but who did not receive payments accurately reflecting that, will likely be receiving payment in full in the coming weeks.

Any Americans who have not received any or all of the stimulus money that they are entitled to but have not yet filed their 2020 tax return must do so before the extended tax day deadline of May 17.

Eli Fuhrman is a contributing writer for The National Interest.