US President Donald Trump has promised to send $500 (£370) to nearly one million Americans, as refunds for what he described as “Obamacare overcharges” collected during the Biden administration.

The refunds, to be sent out starting in October, will go to people in 30 states who buy health insurance through the federal marketplace and do not receive financial help, according to the White House.

Officials said the payments were meant to refund Americans who faced higher premiums and who paid the full cost of their plans.

The promised refunds are on top of the $5,000 payments Trump recently pledged to send Americans if Republicans win control of Congress in November’s elections.

Obamacare, formally known as the Affordable Care Act, is the health law passed in 2010 that expanded access to insurance and set national rules for coverage.

It created online marketplaces where people can buy private health plans, often with government assistance that reduces monthly costs.

The marketplaces are operated either by individual states or by the federal government, and people who buy plans through the federal exchange pay monthly premiums. Those who do not qualify for income-based subsidies pay the full cost themselves, which can run to hundreds of dollars a month.

In a fact sheet released on Thursday, the White House said that these consumers were “most exposed” to marketplace “user fees” that it said were added to premiums.

It went on to say that fees collected under President Joe Biden were “far in excess of what was needed to run the exchange”, and had created a surplus.

The fact sheet did not say how large the surplus was, or if there were plans to lower fees and premiums in the near future.

While most Democratic lawmakers have not yet responded to the announcement, they have previously defended the law as a key source of affordable health coverage.

Trump attempted to repeal Obamacare in his first term, and in his second has sought to change it. He has repeatedly called for it to be replaced, although he has not outlined a detailed alternative. The rebate plan marks one of his most direct actions involving the law since returning to office.

Medicaid, public health insurance for lower-income people, and Affordable Care Act marketplace enrolment has fallen by about 8 million people since Trump returned to office.

However, the law’s largest coverage-related changes under the One Big Beautiful Bill Act (OBBA) are not yet in effect and are expected to take several years to be fully implemented.

Payments would cover people in states including Florida, Texas, North Carolina, Ohio, Michigan, and Wisconsin. Cheques will be mailed directly to eligible households, the administration said.