Health insurers will gain $1 trillion in new revenue over the next eight years under the 2010 health-care law, assuming it is upheld by the Supreme Court, according to a Bloomberg Government study.

The amount is equal to about one-half percent of the nation's estimated gross domestic product from 2013 to 2020. Insurers would keep about $174 billion - $22 billion a year - for profit and administrative costs. The money comes from U.S. subsidies to people purchasing insurance beginning in 2014 and an expansion of Medicaid, the government's health program for the poor.

The Supreme Court is weighing whether the law's requirement that most Americans carry health insurance is constitutional. If it is not, the court will decide how much of the law to strike down. Should the law survive the court's review and Republican efforts at repeal, it is projected to expand insurance to 32 million Americans who lack it by 2016.

"It's a confirmation of, one, how much money we're spending as a nation on health care; and two, how much is riding on this court case and the Supreme Court's decision," Matt Barry, a Bloomberg Government health analyst and the study's author, said in a phone interview.

About 9 percent of the insurance industry's total revenue from 2013 to 2020 hinges on whether the health law stands, according to the study.

Starting in 2014, states are required to open new insurance marketplaces called "exchanges" that will sell subsidized policies to people who do not get coverage through their jobs. People who earn wages close to the poverty level, about $23,000 for a family of four in 2012, will be made eligible for Medicaid.

Barry's study calculates that subsidizing private insurance premiums will cost taxpayers $557 billion through 2020, while the Medicaid expansion will cost the federal government $669 billion. The two provisions account for 98 percent of new spending in the law, the report said.

About 58 percent of that spending would pass through insurers.

Under the health law, insurers must spend at least 80 percent of their premium revenue on medical care, so most of the $1 trillion will flow to hospitals, doctors, and other health providers.

"This is a law that's good for consumers and good for business, and there are a trillion reasons why it's good for the insurance industry," said Ethan Rome, executive director of Health Care for America Now!, an advocacy group that supports the health law and is critical of insurers.

The insurance industry, through its Washington trade group, America's Health Insurance Plans, provided about $86 million to the U.S. Chamber of Commerce in 2009 to help fund a lobby and advertising campaign against the law. A spokesman for AHIP, Robert Zirkelbach, declined to comment on the Bloomberg Government study.