The Board of Education and the union representing 500 top-level school administrators have reached tentative agreement on a new three-year contract that would provide an immediate 5 percent pay raise. The pact also includes a clause that would require a "better-than-satisfactory" performance rating to merit pay raises after the fourth year of employment.

The pay package is identical to a contract tentatively approved by the board's 1,400 school aides and clerical employes, according to Athel Liggins, executive vice president of the D.C. Council of School Officers, which includes principals, assistant principals and central office administrators. The 5 percent raise would be retroactive to last Nov. 1, plus a 3.5 percent bonus. The proposal also includes a 7 percent raise for fiscal 1983 and 6 to 8 percent the next year, according to a scale indexed to the cost of living.

Administrators are on probation for two years and get automatic pay raises if their job performance ratings are satisfactory, Liggins said. Under the new clause, a satisfactory rating no longer would be sufficient for a raise to step 5 of the 8-step scale, he said. Reviews would be made annually.

Reviews would be conducted by each administrator's supervisor and the council would take steps to assure that ratings are "fair and unbiased," Liggins said. The council will vote on the contract March 3, he said.