More than a million government retirees would get the health insurance refunds being offered to about the same number of federal workers under a bipartisan bill introduced yesterday in the House.

The bill, which could be approved as early as today by the compensation subcommittee of the House Post Office-Civil Service Committee, would also cut premiums next year for most federal workers and retirees by raising the government's contribution to their health insurance.

Eleven federal health plans are planning to give some kind of cash refunds to current subscribers, including about 300,000 workers and retirees in the Washington area. The Reagan administration supports the refunds for both employes and retirees, but until the federal health insurance law is changed, only workers can get them.

Blue Cross-Blue Shield, the largest plan in the federal program, was the first to offer refunds, which will range from $18 for postal employes with standard-option coverage to more than $400 for white-collar civil servants enrolled this year in the high-option plan.

Other health plans, including those for Aetna, the American Federation of Government Employees, Government Employees Benefit Association, Government Employees Hospital Association, the Foreign Service and the Letter Carriers, are also proposing to make refunds.

The refunds are made possible because policyholders are not using their insurance as often as they once did, or are paying a bigger share of their medical bills.

The legislation, introduced by Rep. Mary Rose Oakar (D-Ohio), would also raise the government contribution rate for individual premiums, currently limited to 75 percent.

Under the complicated formula used to arrive at the premium share, based on premiums charged by the six largest health plans, the government pays an average of 61 percent of the premium for white-collar workers and up to 75 percent for postal workers.

The Oakar plan would also require the government to "encourage" health plans to improve psychiatric benefits, which have been cut back in recent years along with other benefits, and to hold annual open enrollment periods when employes and retirees can change health plans.