Most of the government's 135,000 white collar managers and supervisors -- including about 60,000 people here -- are in for a jolt this October when they take a look at their new pay raise.

In most cases the chiefs will get a 2.4 percent raise (maybe a tad more) while the people they supervise and manage will be getting about double that amount, or something like 4.8 percent.

Reagan: Beginning Oct. 1, the start of the government's fiscal year, all federal agencies are required to have a "merit pay" system in place for those Grades 13, 14 and 15 (pay range $32,048 to $50,112.50) that guarantees persons designated as managers or supervisors only one-half of the regular percentage increase other workers get.

Later this year -- or early in 1982 in some agencies -- supervisors and managers who merit it will get additional increases. Some will get nothing. Others will get raises above and beyond the 4.8 percent range, retroactive to the first pay period beginning on or after Oct. 1.

Bureaucratic Washington is about evenly divided on the issue of merit pay. That is: half the people are confused by it. Merit pay is one of the management time-bombs left ticking by President Carter's civil service reform act, whose main contribution to date has been to abolish some agencies and create new ones with new names to replace those abolished.

Merit pay means just that. You get what you are worth -- according to your boss. Workers placed under merit pay are, by law, guaranteed only one-half of the regular October percentage pay rise that goes automatically to other white collar civilians. Agencies now are working up elaborate systems, and training people, to handle merit pay.

To finance merit pay raises, the GS 13, 14 and 15 people no longer will be eligible to get longevity pay raises -- worth about 3 percent -- that are routinely given out to workers who maintain an "acceptable level of competence." What that means is that 99 percent of the people get them when they come due. Money from the longevity (or within grade) raises that an agency would have given out will be put in a merit pay pool, augmented by funds that formerly were used to give those worthy employes quality step increases (QSIs).

Individuals in the merit pay pool will compete with their peers for raises. Merit pay has been tested in eight federal agencies, which converted to the system last year and paid several thousand of their GS 13, 14 and 15 people under the new system. Those agencies were the Civil Aeronautics Board, Civil Rights Commission, Environmental Protection Agency, Farm Credit Administration, Metric Board, Office of Personnel Management, Small Business Administration and Selective Service System. Merit pay people in those agencies got only 4.55 percent in the first round, while other federal workers got a flat 9.1 percent raise. Later on, many employes -- the numbers and percentage vary by agency -- got raises ranging from 24 percent to 0.The average increase for persons under merit pay (in a year when other workers got 9.1 percent) was just under 12 percent.

If the merit pay plan works out as well as top officials hope, you can bet that somebody in Congress or the White House will propose extending it down the GS ladder to Grades 1 through 14. Merit pay still is a cloud on the horizon for most workers, but for supervisors and managers it is almost here.