Nearly 1 million Americans are getting a $500 refund check from the federal government, but where they live determines whether one arrives.

The Treasury Department began mailing the checks on September 30, to more than 950,000 people in 30 states, ABC News reported on October 1.

An administration official told the network that those states rely on federal exchanges run by the Centers for Medicare & Medicaid Services.

However, residents of the other 20 states will not receive the $500 ACA refunds because their states run their own health insurance exchanges, meaning the federal government did not collect the user fees tied to the payments, ABC News added.

According to The U.S. Sun, the 20 states that will not receive the checks are California, Colorado, Connecticut, Georgia, Idaho, Illinois, Kentucky, Maine, Maryland, Massachusetts, Minnesota, Nevada, New Jersey, New Mexico, New York, Pennsylvania, Rhode Island, Vermont, Virginia and Washington.

However, living in one of the 30 eligible states doesn’t automatically qualify someone for a check.

According to CNBC, the checks are going mainly to people earning more than 400 percent of the federal poverty level who bought coverage without premium subsidies.

Some unsubsidized buyers earning between 100 percent and 400 percent also qualify. No application is needed, Deseret News reported October 2.

As First for Money previously reported, President Donald Trump has claimed the money was wrongly collected.

In a video announcing the plan, he claimed without evidence that the Biden administration sat on a pool of unused surplus funds, ABC News reported.

“For years, the Biden Administration overcharged you to fund the operation of HealthCare.gov,” reads a letter that comes with the checks. “That money belongs to hard-working Americans, not the Government, and now, I am returning it to you.”

The $500 checks are separate from a one-time $90 rebate going to eligible Original Medicare Part B beneficiaries.

NBC News reported that a CMS fact sheet estimated the number of eligible people at 20.8 million.

Some are expected to receive a direct deposit in early October, while others are expected to receive a paper check from the Treasury later this month.