Because of congressional action to put federal-military pension increases and Social Security raises on the same timetable, the 150,000 retired civil servants and military personnel here have received only a 3 1/2 percent cost-of-living raise in the last 27 months.

Now, because of last-minute budget compromising, there is a chance Congress may once again stick it to government retirees.

At one time, federal-military retirees got much more generous cost-of-living treatment -- twice-yearly raises -- than did Social Security recipients. To equalize treatment and save money, Congress and the White House put U.S. retirees on the same one-raise-per-year cycle. To make those raises coincide, increases for federal-military retirees were delayed twice. Last January, both Civil Service and Social Security retirees got the same 3 1/2 percent raise, and the principle of "linkage" was established.

Now, however, Senate-House budget conferees are considering a plan that would allow persons under Social Security to get raises next year, but slap a one-year freeze on other federal benefit payments, including Civil Service and military retirement.

The Senate originally proposed freezing all federal pension payments next year for a saving of $29.2 billion over three years. The House still wants Social Security raises -- which go to one in every six Americans -- paid next year. But the two sides must reach a compromise.

If the conferees agree to allow Social Security increases next year, the obvious place to look for savings is in Civil Service-military retirement benefits, which go to a much smaller group (3.1 million people). Freezing non-Social Security federal benefit raises next year (including some veterans' payments) would produce a $7.2 billion savings over three years. About $4.8 billion of that would come from freezing Civil Service-military pensions.

Federal and postal unions, and civilian and military groups are arguing that their people should get the same treatment as persons under Social Security. If they lose, retirees will have another long, long wait before their next adjustment.