Federal workers who will be hit with an average health insurance premium rise of 31 percent in their next paycheck are stuck with their current health plan (and any new premium increases) until at least the middle of February. It is entirely possible that the 9.2 million government workers, retirees and their families will be locked into their health plans for the rest of the year.

The question of when/if to hold an "open season" enrollment period (when feds, postal workers and retirees can shop for new insurance deals) is before the U.S. Court of Appeals. The court will decide whether the Office of Personnel Management acted within its authority last year when it canceled an open season that was due to begin in November and run through mid-December.

OPM issued an administrative order postponing indefinitely the open season on grounds that court battles over its earlier attempts to force insurance companies to drop certain benefits and reduce others (to decrease 1982 premium increases) made it impossible for OPM to produce, proofread, print and distribute brochures outlining changes in the 130-plus plans within the federal health program.

Federal unions and some insurance carriers say that OPM caused most of the delays, and that it is trying to defer an open season to protect Blue Cross/Blue Shield. Those programs cover more than half of all federal workers, and they and other carriers with big premium increases could lose many subscribers during an open season. Biweekly premiums for its high-option family plan are up $11.25, one of the biggest increases in the federal health program this year.

The issue before the court (in a lawsuit filed by the National Treasury Employees Union) is whether OPM had the authority to indefinitely postpone the open season. Among the ways the court might rule are:

1. That OPM did have authority to postpone the open season indefinitely. That would mean the next open season would come when OPM decides to hold it.

2. That OPM had the authority to postpone the open season at the time, but now that premium and benefit levels have been established, it should reconsider holding an open season as soon as possible.

3. That OPM did not have authority to defer the open season, and that it should schedule one immediately.

There is no deadline for court action, but insiders expect some kind of ruling by the second week of February. Until the court acts, federal employes and retirees are stuck with their health insurance plan no matter how much premiums are up or benefits are reduced.