WASHINGTON—The federal government has approved about 2,000 applications from employers seeking partial reimbursement of health care costs incurred by early retirees, Health and Human Services Secretary Kathleen Sebelius said Tuesday.

The Early Retiree Reinsurance Program, which is part of the Patient Protection and Affordable Care Act, calls on the federal government to reimburse employers for a portion of health care claims incurred by retirees who are at least age 55 but not yet eligible for Medicare, as well as by retirees’ covered dependents, regardless of age.

After a participant in an early retiree plan 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 on June 1 or later.

During a news conference announcing the acceptance of the applications, Ms. Sebelius said “we don’t know” how many retirees and eligible dependents will be affected by the first round of approvals. The program covers private, public and nonprofit organizations, including labor unions.

Congress has appropriated $5 billion for the program, which is seen as a way to encourage employers to continue their early retiree health care plans until at least 2014.