Beginning next spring, the Prince George's County school board will have to account for each school where racial percentages are out of line with court-ordered guidelines, under an impending order from a Baltimore federal court judge that was released yesterday.

Federal District Court Judge Frank A. Kaufman notified the school board and the NAACP, parties in a lingering county school desegregation case, of this and other proposals yesterday. Barring "good cause shown in writing" by either party, Kaufman said, he will make the order official on Sept. 19.

Neither school board president Susan Bieniasz nor NAACP vice president John Rosser would comment on Kaufman's proposed order.

The order is similar to a list of tentative measures Kaufman had outlined in his June ruling on the case. The NAACP had charged that county schools were racially segregated and that black students were discriminated against in discipline, classes for talented students, and in special education.

Kaufman found that the school practices did not amount to intentional discrimination in those areas.

At the same time, he concluded that the school system had never achieved a "unitary status," that is, it never had fully integrated what had been until 1973 a separate school system for blacks and whites.

Kaufman's proposed order changes percentage guidelines for racial balance that Kaufman established in 1972 in order to dismantle the dual school system. The 1972 order said that no school should be less than 10 percent or more than 50 percent black.

The new guidelines establish an upper limit of 80 percent black, reflecting the large increase in the number of black students in the schools since 1972.

As of September 1982, three of the county's 20 high schools and three of 28 middle schools were more than 80 percent black. Of 128 elementary schools, 23 were more than 80 percent black, while two were less than 10 percent black. The school system as a whole was 53.9 percent black last year.

In addition, Kaufman proposes to continue the requirement that no student be bused more than 35 minutes each way for purposes of desegregation.

School officials had argued in court that in most cases further desegregation of predominantly black schools would involve busing white students from the extreme northern and eastern areas of the county, which they said would entail bus rides of more than 35 minutes each way.

"I assume that the 35-minute guideline and the geographic concentration of blacks may well inhibit the ability of the school system to make changes," school board lawyer Paul Nussbaum said yesterday.