Job and promotion-seekers will have their best shot in years next month as thousands of top-paying jobs open up with the nation's largest employer -- Uncle Sam.

An astonishing number -- 230,000 -- of federal workers are eligible to retire right now. Many of them, especially persons in the upper pay brackets, have special incentives to retire before the end of February. As pointed out here yesterday, top-paid, long-service bureaucrats can boost their lifetime pensions nearly $5,000 per year IF they retire before March 1.

On March 1 a new cost-of-living raise goes into effect for federal and military personnel. It is expected to be worth around 6 percent. Individuals who retire before that effective date also will be able to "reach back" and take advantage of all or most of a 6.9 percent cost-of-living raise retirees got last September. If they retire later they will lose the September raise, which was record-high.

Annuities of the 2-million-plus retired federal workers (their survivors) and military people are linked to the cost-of-living. There are more than 100,000 retirees in metro Washington alone.

Pensions automatically are adjusted according to the Consumer Price Index. Raises go into effect every six months, in March and September. They first show up in annuity checks received in April and October of each year.

While federal retirees' pensions are linked to the cost-of-living, federal pay raises are not. Government experts project an October 1980 raise of around 6.2 percent for federal workers (and military personnel) despite an annual inflation rate more than double that amount. Retirees, linked to the inflation rate, never catch up but they move along with it. The twice-yearly raises give them the advantage of compounding.

Long-service federal executives (at the $50,100 pay range) have been hit with frequent pay freezes. For several years they were passed over for raises. That is an important incentive to retire, since federal pensions are based on service and the high 3-year salary average.

Once an empolye works beyond 40 years in government he or she is entitled to the maximum 80 percent of salary as a pension. There is no longer any incentive to keep working to build up a pension if executive rates are frozen or move up only slightly. (Last October rank-and-file federal workers got a 7 percent pay raise while some executives got 5.5 percent, and some no increase at all.)

The combination of frozen or low pay raises for executives, the high inflation rate pushing up retired pay and the chance to recapture the record 6.9 percent September 1979 raise will push many senior officials and employes into retirement. The last time a somewhat similar situation occurred, in mid-1973, more than 50,000 people retired.

All of the above are reasons top federal brass are expecting lots of retirements in February. Smart job-hunters already have filled in the necessary forms and taken the tests needed to get on with Uncle Sam. People inside government who want to move up are checking with friends in personnel, and watching the retirement party lists, to see for whose job they may bid.

February will be a month of mobility -- in, out and up -- for the federal work force. If the rate of inflation is cut, this could be the last year for double-digit retiree raises. Don't bet on it, however.