Many political appointees in the Reagan administration are switching to the new Federal Employees Retirement System because it offers them -- and other relatively short-term workers -- the opportunity to get substantial tax-free refunds on money they've put into the old Civil Service Retirement System. The same attractive option also is available to recently elected members of Congress.

An informal survey by this column of a half-dozen federal agencies indicates that while many career workers are delaying a decision on any pension plan switch, a lot of political appointees have already made the move.

Most workers hired before Jan. 1, 1984, must decide by the end of this year whether to stick with the old retirement plan or go into the new FERS program.

Workers with less than five years of federal service who join FERS can get back most of their contributions to the old pension plan. Most people covered by the CSRS contribute 7 percent of pay to it. Under FERS, which offers a smaller civil service pension, employes contribute only 1.3 percent of salary toward their own annuities although they do pay the full Social Security tax.

Eligible people who move into FERS can get refunds equal to about 5.7 percent of the total amount of money they have already paid into the old pension plan. For some top-salaried people that would amount to $15,000 or more.

Although the refund is available to most employes with less than five years of service, it is especially attractive to political appointees whose careers will probably end shortly after President Reagan's successor takes over.Job Mart

Interior has openings for secretaries {typing} at Grades 4 or 5. Call Betty Davis at 343-7645.

Bureau of Labor Statistics wants a GM 13 ($38,727) supervisory printing specialist. Call JoAnn Coley at 523-1107.

The Architect of the Capitol has vacancies for electrical, elevator and HVAC engineers, Grades 11 through 14; a clerk-steno, GS 3/5; elevator and electronics mechanics, WG 10/12, and a GS 12/13 financial manager. Call 226-2546.

National Institutes of Health in Bethesda needs a personnel management specialist, GS 9 through 12, and clerk-typists, GS 2 through 4. Call 496-6477.

Federal Home Loan Bank Board has several openings for Schedule C {noncareer} secretaries at the GS 7 through 9 level, and for clerk-typists, GS 2 through 4, and secretaries, GS 4 through 6. Call 377-6060.

Agriculture's Food Safety Inspection Service wants a GM 13 visual information officer. Status required. Call Velinda Magana at 447-6617.

Army has an opening at Cameron Station for a GS 5/6 supply technician {typing}. Call 694-0103.

Andrews Air Force Base is looking for a temporary flight records clerk, GS 5. Call 981-5431. Top Executives

The Federal Executive Institute Alumni Association is taking nominations for the executive of the year awards for the federal, state and local government sectors. Last year's winners were Fred C. Fischer, Agency for International Development, and Stuart R. Connock, Commonwealth of Virginia. For details call Joseph M. DeBose at (703) 250-6739.