Many of the government's 106,000 managers and supervisors who are under a pay-for-performance system will get some kind of pay raise this October, even if their subordinates have to wait until January for a pending 4 percent increase.

Office of Personnel Management officials say the merit raises for employes in Grades 13, 14 and 15 could be as high as 6 percent if they get outstanding ratings from their agencies. OPM is in the process of working up guidelines spelling out how agencies are to handle the upcoming merit-pay raises. But several federal personnel directors who are much closer to the action say it is more likely that the top raises will be in the range of 2 percent to 3 percent.

White-collar federal workers are supposed to get a catch-up-with-industry raise each October unless the president or Congress delays it.

President Reagan wants to hold off on the 4 percent adjustment until next April. The Senate and House have tentatively approved the raise to begin Jan. 1, 1984.

Most white-collar employes get the full amount of the general increase automatically. But supervisors and managers under the merit-pay system--and that includes about 50,000 people here--are guaranteed only one half of the regular percentage pay increase. Any additional increase they get depends on their performance ratings, how those ratings are distributed, and how much money the agency has in its merit-pay fund.

The merit-pay system, a legacy from the Carter administration, does not allow automatic in-grade (longevity) raises, which are worth 3 percent, for supervisors and managers drafted into the system. Rank-and-file workers get the raises automatically every one to three years.

If there is no regular federal pay raise this October, agencies will still give merit-pay raises to some of their supervisors and managers. In agencies where most employes get top ratings, the increases will be small. In those where only 10 percent to 15 percent get ratings of "outstanding," OPM says the increases could be about 6 percent.

In addition to any merit raises they may get this October, the supervisors and managers will also automatically get half of the percentage of the next general federal pay raise, or about 2 percent this January or next April.

Even with the October merit raises, most supervisors and managers will still be getting smaller percentage increases than their subordinates, who are still eligible for the automatic in-grade raises.

The Reagan administration hopes to extend the pay-for-performance system to most other federal employes and eliminate automatic in-grade raises. Congress has told the OPM not to put the rules change into effect until Oct. 15.

Despite congressional opposition to the merit-pay plan, the OPM thinks it can work out a compromise that will be acceptable. In his nationally broadcast radio address last Saturday, President Reagan gave the proposal another plug. He said:

" . . . There's been a lot of talk about my call for merit pay to reward outstanding teachers. . . . Well, I think the same principle should apply to the federal government itself. Earlier this year, we announced a proposal to require federal employes to earn, not just automatically inherit, their pay raises.