Federal workers confused by their 1980 health insurance options will get more time -- up to 30 extra days -- to decide which policy is best for them.

In addition, area workers who already have selected one of the 106 available insurance plans will be allowed to cancel their first choice and switch to another plan. What they must do is say their original decision was based on incomplete information supplied by the government.

Federal health insurance premiums are going up an average 10 percent in January. U.S. federal and postal employes are in an "open season" that ends Dec. 7, when they must decide what coverage they want for 1980. Rates between the plans vary as much as $500 a year, and benefits depend on price and individual plans. It is a major financial and emotional decision that federal households must make.

Although the government will not offer a blanket extension past the Dec. 7 deadline, individual workers in Washington, Chicago and Philadelphia will be able to request more time to pick a plan.

Within a next few days the Office of Personnel Management will be sending a special advisory to health insurance officers in major agencies in those three cities, advising them that they have authority to grant employes individual extensions of time -- up to the first week in January -- to select insurance.

The confusion stems from the fact that more than 100 plans (some with two, three or four options), are offered within the federal health insurance program, the world's largest civilian health plan. This year Uncle Sam, in the person of the Department of Health, Education and Welfare, ran into trouble when he tried to encourage employes to switch to health maintenance organizations (HMOs) to save money.

HEW printed up more than 500,000 brochures. They compared some benefits offered by local HMOs with Blue Cross-Blue Shield and Aetna, the two largest federal insurance carriers. Plans sponsored by unions and other groups objected, saying the HEW brochures gave Aetna, Blue Cross-Blue Shield and the HMOs an unfair edge and implied government endorsement.

The American Federation of Government Employes (it has its own health plan) took the case to U.S. District Court here. The union asked the court to block distribution of the HEW flyers, and to extend the open season period past Dec. 7, but most of the brochures already had been given out.

The court did tell the Office of Personnel Management to advise workers that the brochure was "incomplete." And OPM has quietly agreed to give employes extra time to study plans if they ask for it or to make changes from plans already selected this open season. But it is not taking out full-page newspaper ads to advise people of the extra time.

A couple of things to bear in mind:

This is not an automatic extension for everyone everywhere. It is local, and in Chicago and Philadelphia. And you must ask for it based on the claim that you have been confused by "incomplete" data supplied by government.

You may have to be persistent to get results. Most agencies will not acknowledge the extension until OPM spells out the gospel in form of an advisory bulletin and a FPM (Federal Personnel Manual) insert. OPM is not anxious to encourage everybody to ask for the extension, or change plans if they already have picked one. Paperwork, you know. But you do you have the right to make the change, or get the extra time if you go about it correctly.

Whatever Happened To . . .? Employes of the ACTION agency have been hearing a familiar voice on the CBS Evening News. It is Carol Honsa. She's a onetime ACTION public affairs specialist now in Pakistan "stringing" for Newsweek, and CBS. Honsa's husband, Stuart Auerbach, is the The Washington Post's india-based correspondent.