SAN FRANCISCO (MarketWatch)—This summer, your health-insurance costs could go down for a change.

A provision in the federal health-reform law stands to return big bucks to customers whose health plans have exceeded the limits of a formula meant to ensure that most premium dollars go to pay for medical care instead of overhead and profit.

Under rules set in the Affordable Care Act that Congress passed and President Obama signed in 2010, individuals and employers will begin receiving a total of $1.3 billion in rebates by Aug. 1, according to an analysis by the Kaiser Family Foundation, a nonpartisan research group.

Consumers and businesses in Texas and Florida will see the largest rebates, with $186 million and $149 million, respectively. Hawaii is the only state where no insurer is projected to issue a rebate.

Rebates will come either in the form of a check or in premium discounts or “holidays,” where consumers can skip a month or two of payments until the debt zeros out, said Cynthia Cox, the study’s co-author and a fellow at the Kaiser Family Foundation in Menlo Park, Calif.

“It’s going to be one of the more visible aspects of reform until some of the major provisions go into effect in 2014,” she said. “It’s going to be one that gets a lot of attention from consumers.”

Some of the biggest beneficiaries will be people who buy insurance on their own, who don’t have to worry about sharing the money with an employer that covers a substantial portion of their premium costs. Nearly a third of those in the individual market are expected to receive rebates, compared with 28% of the small-group market and 19% of the large-group employer markets.

Rebate amounts vary by state and by insurer. Consumers slated to get rebates in the individual market are forecast to receive $127 on average. Amounts can range from a few dollars in some states to as much as $305 in Alaska, $294 in Maryland and $243 in Pennsylvania.

Rebates to people in the individual market are expected to hit $426 million, while small businesses are on track to receive $377 million, according to the report. Rebates in the large-group market, which has the most enrollees, will total $541 million.

But big employer plans also have the highest bar to meet. Under rules designed to calibrate what’s known as the medical-loss ratio, large-group health plans need to show that they spend at least 85% of the premium dollars they take in on medical claims and quality improvement as opposed to administrative costs, marketing and profits. The ratio is set lower in the individual and small-group markets, where insurers need to spend just 80% of premiums on actual medical care.

Insurers that fall below these thresholds have to issue refunds to consumers and businesses. But the details can be complicated for employer plans because of how premiums are split between workers and employers and the different regulatory agencies overseeing the process, Cox said.

Still, people who are in plans that aren’t required to send them rebates already may have benefited from the medical-loss ratio provision since some insurers may have lowered their premiums to be in compliance when the rule took effect in 2011, she said.

“Insurers have kind of built these requirements into how they structure their premiums,” Cox said.

Kaiser Family Foundation researchers based their rebate data on insurers’ estimates in filings to the National Association of Insurance Commissioners. Researchers aren’t sure how the rebates may change from year to year, Cox said.

“Right now, utilization of health care services is relatively low because of the economy,” she said. “People aren’t going to the doctor as much because it costs money. Normally when utilization goes down, that’s when insurers make income because they’re taking in the same amount for premiums but paying out less in claims.”

With the new medical-loss ratio rule, insurers have to pay the excess back to enrollees, Cox said. “People who aren’t using as much health care are essentially getting that money back rather than the insurers keeping it.”

The arrival of rebates is likely to play to President Obama’s advantage in an election year. Americans generally favor components of the health overhaul such as allowing adult children to stay on their parents’ plans until they’re 26 and barring insurers from discriminating against people with pre-existing health conditions. But approval is lower for the comprehensive package.

Perhaps the biggest threat to rebates hitting mailboxes as planned is the Supreme Court ruling, expected by the end of June, on whether health reform can require people who don’t have insurance to buy it or face penalties. Proponents argue the so-called individual mandate is crucial to making the insurance market work by spreading risk as more sick people gain coverage. But if the Supreme Court finds the mandate unconstitutional, it may effectively unravel some or all of the health-reform features already in place.