WASHINGTON—Thousands of employers and other retiree health care plan sponsors are flocking to a one-time $5 billion government program that will partially offset claims incurred by pre-Medicare-eligible retirees and their dependents.

Last week, the Department of Health and Human Services made public the names of about 2,000 employers and other sponsors whose applications to participate in the Early Retiree Reinsurance Program had been approved.

Approvals include corporate giants, such as IBM Corp. and Wells Fargo & Co.; big cities, such as Dallas and Philadelphia; huge union plans, such as the trust created under a 2007 agreement between Chrysler, Ford and General Motors with the United Auto Workers that allowed the automakers to unload tens of billions of dollars in retiree health care obligations in exchange for contributions to the trust; and numerous small cities, such as Evergreen Park, Ill., a southwest Chicago suburb with a population of about 20,000.

In all, 32% of the approved applications came from businesses, 26% from state and local governments, 22% from union sponsors, 14% from schools and other educational institutions, and 5% from nonprofit organizations, HHS said.

The list will continue to grow in the weeks ahead as the government regulators review pending applications. HHS hasn't said how many applications, which were released in June, are in the pipeline.

It isn't surprising that interest in the program is so widespread, experts said.

“It is found money,” said Rich Stover, a principal with Buck Consultants L.L.C. in Secaucus, N.J.

“This is a welcome way for employers to reduce their retiree health care costs, as long as the federal money lasts,” said Frank McArdle, a consultant with Hewitt Associates Inc. in Washington.

Hewitt estimated the reimbursement could save employers $2,000 to $3,000 per adult 64 and younger enrolled in their plans.

Under the program—embedded in the new health care reform law—the government will reimburse employers for a portion of health care claims incurred by retirees who are at least age 55 but not eligible for Medicare, as well as retirees' covered dependents, regardless of age.

After a participant incurs $15,000 in health care claims in a plan year, the government will reimburse plan sponsors for 80% of claims up to $90,000. The reimbursement applies to claims incurred June 1 or later. In general, the reimbursement must be used to reduce employers' and/or retirees' health care costs.

As part of the health care reform law, Congress appropriated $5 billion for the program, which was seen as a way to encourage employers to continue their early retiree health care plans until at least 2014. That is when many key provisions of the health care reform law kick in, including establishing state pools, where lower-income individuals can use federal health insurance premium subsidies to purchase coverage.

The program is authorized to continue through Dec. 31, 2013, or until the $5 billion runs out, which the Employee Benefit Research Institute in Washington has projected will occur sometime next year.

Some say an additional appropriation of funds is unlikely.

“Right now, money is scarce and no one is talking about adding more funds. Whether that changes will depend on the composition of Congress” after the November elections and the state of the economy, Mr. McArdle said.

The program's next step is the release of application forms for approved plan sponsors to file reimbursement claims. Government regulators said those forms will be made available sometime this month, but haven't been more specific. Reimbursement checks should begin to flow sometime in October, regulators have said.