The departure of Republican jobholders and their replacement by Democratic political appointees will not be affected by President Carter's partial freeze on other incoming government job traffic.

Last week, Carter told federal agencies to reduce hiring by filming only three of every four vacant jobs.

The semi-freeze was made retroactive to Feb. 28 and will continue through April or early May for most agencies. Some departments that will receive new, low personnel ceilings nex month may be forced to continue the three of four job exercise for much longer.

Carter's order said he wants to reach the new lower personnel ceiling via attrition, and agencies were cautioned against contracting work or jobs to private industry to meet the new quotas.

The Postal Service, which has 600,000 workers or about one fourth of the federal work force, has been exempted from the freeze. Other exemptions are:

hiring that, at the discretion of the agency or department head, is "necessitated by emergency situations involving the safety of human life and protection of property."

Programs such as those designed for veterans, minority groups or students.

Reassignments of personnel within but not between agencies.

Executive appoinments in Levels 5 through 1 which pay from $47,500 to $66,000. Supergrade jobs in Grades 16, 17 and 13 are not exempt from the freeze even though many pay the same $47.500 rate as executive level 5.

Shifting of employees form one agency to another because of a transfer of functions resulting from presidential reorganizations actions.

An important point, of which few agency managers are aware, deals with the Feb. 23 effective date of the freeze action. An example of what that means: Suppose an agency had an onboard-strength of 100 jobs as of Feb. 28 and had 10 vacancies. Under the language in the implementing order, that on-board-figure is set at 90 and the three-for-four procedure would be based on a ceiling of 90 jobs, rather than 100.

Most agencies will know their new personnel ceilings, at least informally, by April 1. Those are at or below their new ceilings then will be taken off the freeze, and normal hiring will resume. Ceilings may not be exceeded. Others will have much tougher job targets based on new ceilings.For them, the freeze could last much longer.

The order actually says the directive will remain in effect until Sept. 30, 1978. Most agencies will be free of it by that time, but the order could extend through that time periodif they have not met their job ceilings.