Federal agencies have until the end of the year to give out peformance raises called for in a newly revised merit system for middle-- and upper-- level supervisors and managers, including 50,000 here.

The complex guidelines, detailing how to figure raises for Grade 13 through 15 employes earning between $37,000 and $67,000 a year, were sent to federal personnel directors last week.

The directors must translate the guidelines into workable English (some job, as you will see in a minute!) and have the new system in effect by Dec. 31. Raises will be retroactive to the first pay period of this month.

Most people covered by merit pay -- nationwide there are about 108,000 -- also will get the regular 3 1/2 percent general pay raise that goes into effect in January for most white-collar federal employes.

Congress approved the merit pay plan two weeks ago as part of an omnibus civil service legislative package called H.R. 2300. Because of the last-minute logjam of bills approved before adjournment, the merit pay plan is still on Capitol Hill. Once the Senate and House sign-off process is completed, the bill will go to the White House.

Reagan administration aides say the president will sign it. Agencies have been given the green light to proceed as if it were law already.

The Office of Personnel Management guidelines say agencies must have a five-tier rating system to rate managers and to use as a basis for raises.

Here are the merit pay instructions OPM has sent to federal personnel directors:

*"An employe in the lower third of the pay range (below the rate for step 4 of the schedule for the grade) who receives a 'fully successful' rating or above shall receive the full dollar equivalent of a step increase the equivalent of a 3 percent pay raise ."

*"An employe in the upper two-thirds of the pay range (at or above the rate for step 4 of the grade) who receives a rating two levels above 'fully successful' (e.g. 'outstanding') shall receive the full dollar equivalent of a step increase."

*"An employe in the upper two-thirds of the pay range who receives a rating one level above 'fully successful' (e.g. 'exceeds fully successful') shall receive one-half of the dollar equivalent of a step increase, rounded to the next higher dollar."

*"An employe in the upper two-thirds of the pay range who receives a 'fully successful' rating shall receive one-third of the dollar equivalent of a step increase, rounded to the next higher dollar."

*"An employe who receives a rating one or two levels below 'fully successful' (e.g. 'minimally successful' or 'unacceptable') shall receive no merit increase."