The nation's biggest "company" health program, which covers half the people of metro Washington and 9.2 million members of the federal family, could be forced to rethink its rate and benefit package if the U.S. Postal Service decides to pull out and set up its own program.

Currently federal employes and retirees pay anywhere from $144 to $1,600 a year for health insurance protection. Rates and benefits vary widely among the 100-plus carriers in the program. And even though benefits have been cut back in the past two years, the average premium has gone up more than 50 percent.

The postal service's 600,000-plus employes, about one sixth of the federal population, already pay smaller health insurance premiums than their colleagues in other federal agencies. That is because postal workers (8 out of 10 are union members) bargain directly with the postal service on wages and fringe benefit matters and their union contracts call for the postal service to pay a major portion of insurance premiums.

But the postal service is concerned about claims processing delays in the Federal Employes Health Benefits Program (FEHB), and by the fact that its health benefits premium cost jumped from $489 million to $642 milllion last year.

Many postal officials think they could get a better, cheaper group health plan if they bargained separately from the rest of the government. The FEHB is controlled by the Office of Personnel Management.

The postal service recently signed a $65,000 contract with the Washington-based consulting firm of Williams, Thatcher and Rand that will decide if the service could, and should set up a voluntary postal health insurance plan.

If the postal service decides to go it alone, it could cause some problems for OPM, for postal unions and for employes outside the postal service. OPM is concerned that the postal service might try to "dump" its retirees into the FEHB so that it could negotiate lower rates for active duty workers. Because they are older, retirees are heavy users compared to younger employes.

Postal employe unions, who use health plans to help build membership, are upset that their plans might be undercut.

Some smaller agencies have toyed with the idea of setting up health insurance plans for their own staffs. But they have been told they must remain in the FEHB. There are health plans that are tailored for the FBI, National Security Agency and CIA workers. But even those agencies do not have their own independent health insurance program. The postal service could do it, however, because it is a semi-independent corporation over which Congress, and the White House, have relatively little control.

It will be early next year before the postal service gets the consultants report and decides what it wants to do. That means that postal workers will be locked in the current FEHB for another year--the next open enrollment period will be in November or December. But somewhere down the road postal employes may get another option, a health plan written just for them.