Washington-area federal workers can save up to $1,200 in premiums and out-of-pocket medical costs next year if they pick the right health insurance plan, according to a consumer group analysis of the Federal Employee Health Benefits Program.

The FEHBP helps pay psychological, dental and other health care bills for more than half the people in the Washington area.

Coverage includes the president, members of Congress and the Supreme Court, U.S. and District government employes, police officers, retired CIA agents and their families. The FEHBP offers more than 150 plans, based from Guam to Georgetown, and is the largest employer-sponsored health program in the nation, and one of the biggest in the world. Most U.S. workers--from astronauts to diplomats--belong to the program.

Washington-area feds are eligible to pick from about 20 insurance plans. They range from nationwide giants, like Blue Cross/Blue Shield, to union-backed plans, local health maintenance organizations (HMOs) and plans limited to special groups, such as folks at the supersecret National Security Agency.

Health insurance premiums will go up an average of 14 percent next year. But price tags vary as much as $1,000 from plan to plan, and benefits differ. Some plans next year will actually cost less than they did this year.

U.S. workers, District government employes and retirees will have a three- week open enrollment period (Nov. 14 to Dec. 9) to study new premiums and benefits. Then they must pick the plan they want for themselves and their families in 1984.

The most detailed help will come from the Checkbook Guide to Health Insurance Plans. The new edition will be released the first day of the open season. The guide, which has become a fall institution in Washington, offers straight facts about plans, premiums and benefits. It also lists which plans are available by category: Are you single? Head of a big family? Are you never sick, or a heavy user of health benefits?

For example, a single person in good health could probably get by with a low-cost plan offering bare-bones coverage. Someone with a large family, or a retiree with special health problems might find it cheaper, in the long run, to pay more in premiums to get so-called Cadillac coverage.

Checkbook editors said yesterday they are still going over galley proofs of the magazine, and won't have final data until the magazine is printed.

But they did reveal that the average family of three in the Washington area could save up to $1,200 next year if it picks a plan with the most modest premiums offering the best coverage. Their best picks are rated on the basis of premiums charged, plus what plans cover, and what they require the insured to pay out-of-pocket.

This year's guidebook will have a special section for retirees. We will devote several columns to the best buys during the upcoming open season, and include a thumbnail sketch of the very detailed and complex Checkbook analysis, when it comes out.

Checkbook was such a success last year that many newsstands sold out of copies early in the open season. Advance copies can be ordered ($4.95) from: Insurance Guide, Suite 406, 1518 K St. NW, Washington 20005. Or call 347-9612 for information.