The Office of Personnel Management yesterday ordered the 112 insurers that write health insurance for 9.2 million government workers, family members and retirees to slash another 6.5 percent from benefit packages they will offer in 1982.

OPM said the carriers have until 5 p.m. Friday to come up with the new cuts -- in addition to a 10-percent average benefit cut mandated earlier by the federal personnel agency -- or get out of the program. About half the people in metro Washington are covered by the federal health plans, and workers pay premiums anywhere from $200 to $800 a year. Insiders predict the average premium increase for next year's plans could exceed 10 percent.

Federal health insurance premiums for this year jumped 16.8 percent. Some carriers offered slightly improved benefits. Costs to government (which pays 60 percent of the premium) rose $375 million this year and employes paid $260 million more for insurance than they did in 1979.

OPM chief Donald J. Devine, with White House backing, wants to cut government insurance costs, partly for fiscal reasons and partly to send a message to the private sector. The Federal Employee Health Benefit (FEHB) program is the largest in the nation.

FEHB includes two giant nationwide carriers, Blue Cross-Blue Shield and Aetna, a score of regional plans (such as the big Kaiser programs in California) a substantial number of health maintenance organizations from Washington to Guam, plus more than a dozen union plans. Union leaders believe OPM is trying to drive them out of business.

The American Federation of Government Employees has been in a long legal fight with OPM over elective abortions. OPM wants to eliminate nonemergency abortion benefits from the 1982 plan. OPM has lost in court, but insists that Congress intends to outlaw non-emergency FEHB abortions. (The House has voted to do it, the Senate has not.) OPM says no carrier offering abortion benefits can participate in the 1982 program. That one is still up in the air.

OPM also wants the American Postal Workers Union to trim 1982 benefits and premiums drastically or get out of the program. Rates charged by the APWU and five other major carriers set the government premium payment pattern for all other health policies.

Devine's letter to insurance carriers was delivered as representatives of 10 union health plans were meeting at the National Association of Government Employees headquarters working out strategy to fight earlier OPM-ordered benefit cuts. With them was a top aide to Senate Majority Whip Ted Stevens (R-Alaska). A spokeswoman said the group was "stunned" by the OPM letter and Friday deadline. She said unions may take the issue to court. The presence of Stevens' aide, and his long-term interest in the federal health program, indicates Congress may get into the act too.

Open Season? There is now real doubt when or if OPM will hold an "open season." The already postponed open season was to start next month. During open season workers may compare premiums and benefits before deciding what plan they want for the coming year.

Things are now more confused then ever. Nobody knows what premiums or benefits will be, which plans will be in the program next year or when workers will have a chance to make changes. OPM says it hopes to have data to employes by early November. The way things are, don't believe it until you see the whites of their brochures.