Neither city offices nor schools are expected to suffer any impact when union contracts with the District government expire at midnight tonight.

The technical expiration of current agreements is of little note, according to both sides in complex talks between the District and a dozen unions representing about 21,000 workers and 6,000 teachers.

In separate sessions around town, government and union negotiators are working on new three-year contracts, including: Pacts covering wages and fringe benefits for seven unions with about 15,000 blue- and white-collar workers. Talks started in August. The city is negotiating separately with those unions about working conditions.

Agreements with the Fraternal Order of Police, which represents about 3,600 officers and sergeants; Local 36 of the International Association of Fire Fighters, which represents about 1,200 firefighters; the D.C. Nurses Association, which represents about 560 registered nurses, and three unions representing about 200 licensed practical nurses. Contracts between the D.C. school sytem and the Washington Teachers Union, under negotiation since June. Talks have been held irregularly, but the pace is picking up, both sides say.

Mark H. Levitt, director of the D.C. Office of Labor Relations and Collective Bargaining, said "productive talks" could soon lead to settlements. Some union representatives, including the firefighters, have said that the city is dragging out negotiations, but the union plans no action against the District.

City law prohibits public employes from striking. Unsettled contract issues are subject to arbitration.

During the last round of negotiations, the police department won larger raises by going to arbitration. "That has to be on the minds" of other unions this year, Levitt said. But he predicted the city would reach agreement without arbitration.

The city's negotiators are Levitt and his former boss, Donald H. Weinberg. Weinberg left the city government and Mayor Marion Barry's Cabinet after revelations that he lived in Maryland while maintaining an address in the District, a violation of Barry's policy that Cabinet members live inside city limits. Weinberg was rehired earlier this year on a contract basis to help handle the negotiations.

Kenneth Nickoles, labor relations director for the school system, said negotiations for teachers will resume tomorrow. The school system opened talks during the summer proposing a 3 percent raise for this year; the union proposed a 10 percent raise.

"Those are just opening figures," Nickoles said. "They're talking points."

William Simons, president of the teachers union, said he is counting on outgoing Superintendent Floretta D. McKenzie to make District teacher salaries more competitive with those paid in the suburbs. "I suspect she'd like to leave here with a good feeling among the teachers," he said.

Simons said the union also is seeking further decreases in class size and a reduction in the number of years it takes a teacher to reach the top salary level.

District teachers with 15 years of experience and a master's degree make $38,054 a year, ranking them behind Fairfax and Montgomery counties and Alexandria.

A new firefighters' contract is being delayed until the D.C. Public Employe Relations Board decides whether the city can change staffing on fire trucks without negotiating changes with the union. Staffing has been a persistent subject of negotiation for 17 years.

Three major unions -- the American Federation of Government Employees, the American Federation of State, County and Municipal Employees and the Teamsters -- represent about 11,000 of the 15,000 white- and blue-collar workers, Levitt said. Other unions representing those workers include the Communications Workers of America, Service Employes International and Laborers International.