Although the government has the machinery for withholding merit pay raises from employees whose performance is unsatisfactory, the odds are 2,000 to 1 against anybody being denied a special, 3 per cent, pay increase on those grounds.

During a recent 12-month period 1,030,000 federal workers got within-grade pay raises for merit. Only 819 employees were denied them, according to government figures.

Carter administration officials have been passing those figures around lately. They clearly hope to shorten the 2,000 to I odds to make merit raises less automatic, and more "meaningful" by making them harder to get.

Officials have rejected the idea of eliminating longevity pay raises for rank-and-file workers. But they are considering a plan that would drop them for middle and top managers. And they are the people who decide who is "satisfactory" an gets a raise, or who isn't satisfactory and therefore does not get a raise.

Longevity pay increases come virtually automatically each year for the first three years of federal service. Afterward they come due every two or three years and, except in unusual circumstances, employees get them routinely. The law says only that an employee must maintain "an acceptable level of competence" before he or she gets the pay raise, which is in addition to regular October pay adjustments for most white collar federal employees. In other words, they must be formally judged and labeled incompetent or unsatisfactory before they can be denied a longevity pay raise.

At one point, key White House aides dealing with the reorganization of the bureauracy wanted to eliminate all longevity increases. They would have substituted a system where supervisors had to go out of their way to nominate employees for the pay increases, and not give them routinely for satisfactory service. But that would require approval of Congress, and it probably would have done more to alienate the President form his 2.6 million workforce than anything imaginable -- short of firing everybody.

White House architects of government "reform" realize they will have to tangle with Congress, federal and postal unions and government workers themselves on some issues. They have decided, however, that it wouldn't be worth the fight to make that issue longevity raises.

On the other hand, federal workers can expect a push from the Carter team to make the in-grade pay raises harder to come by. Phase one of that will begin if the President approves as expected a staff proposal to eliminate the increases for supergraders in Grades 16, 17 and 18, and for thousands of middle grade managers.

One official said the tougher ingrade standards would require a "change in the state of mind" of givernment employees and supervisors. "Now," he said, "you have the situation where everybody gets a raise. If the boss wants to deny one to an employee who is marginal at best, he must go through a lot of red tape, and offend the worker and create a bad relationship. We would like to change that so that people understood that only the extra-effort will get them an in-grade raise, and that there is no disgrace in not getting one." The administration may find that changing the "state of mind" is tougher than it sounds.

Jobs: Public Defender Service wants a Grade 6 legal secretary. Call Rachel Cox at 628-1200.

Commodities Futures Trading Commission has openings for a Grade 11 or 13 personnel management specialist; a GS 11 office service manager and GS 4 or 6 personnel assistant. Call 254-3275.

Defense Personnel Support Center workers in Philadelphia voluntarily produced, wrapped and distributed 1,050 Christmas presents for needy kids in the Philadelphia-Camden area. Hundreds of thousands of federal workers and military personnel around the country also kicked in to make the holiday a better one for senior citizens, orphans and needy youngsters and their families.

Afternoon and Night Work: Federal Trade Commission has immediate openings for part-time clerk-typists and stenos. The jobs are Grade 3 through 5.Hours are 5 p.m. to 9:30 p.m., or Noon to 9 p.m. Call 523-5049.