White-collar federal workers in the Washington area (who currently make an of average $27,577 a year) would get an average pay raise of $1,103--$42.43 per biweekly pay period--starting in January under a compromise okayed earlier this week by Senate-House budget conferees.

Conference members, trying to clear a government budget for the fiscal year that begins in October, split the difference between two different pay-raise dates previously agreed upon by the Senate and House.

The original House budget set next October to start the 4 percent pay raise, despite President Reagan's announced plan to defer that increase until October 1984.

The Senate budget called for the raise to start next April. But senators last week okayed a $9,100 pay raise for themselves, and Senate conferees agreed to move the effective date of the considerably smaller rank-and-file pay raise up to January.

If the Senate and House accept the compromise budget and the president okays it, more than 350,000 civil servants in the Washington-Baltimore area would benefit--although the amount is too little and too late in the opinion of unions, most employes and the government's own pay data.

According to Uncle Sam's own wage survey, white-collar federal employes are due a catch-up-with-industry raise of nearly 20 percent in October. But President Reagan says that the pay survey the government uses is flawed because it only includes selected big industries and does not include salaries paid to state and local government workers. For that reason, and to cut costs, he wants to skip the 1983 raise altogether.

According to the Office of Personnel Management, the average pay of civil servants in the Washington area (not including political appointees or members of Congress) hit $27,577 as of last March. Outside of Washington the average white-collar federal salary is lower ($23,041), according to OPM. The pay differential stems from the fact that most agencies are based here and have more high-grade professionals.

For the average worker here, the before-taxes increase would be $1,103.08 per year--less for lower-grade workers and higher for those in the upper levels.

The compromise budget approved by conferees would defer until January 1985 the next cost-of-living adjustment (COLA) for federal and military retirees, including more than 100,000 here.

That raise is now scheduled to go into effect next June. But the budget compromise would delay the COLAs six months to put them on the same cycle as inflation catch-up raises for persons getting Social Security checks.