With an April 1 deadline looming, nearly half the District of Columbia's 260,000 automobile owners still have not bought 1982 license tag renewal stickers for their cars, the head of the license bureau said yesterday.

Robert O.D. Thompson, the city's assistant director of transportation for automotive services, urged car owners to visit the four sales offices during morning hours in order to avoid long waits in line. Tag sales by mail and the use of credit cards were ended in mid-March.

Above all, Thompson urged, car buyers should avoid visiting the sales offices during the crowded noon hour and should not wait until the final day, next Wednesday.

There are no plans, he said, to keep the sales offices open over the weekend or to extend the Wednesday deadline.

As of Tuesday night, Thompson said, 143,300 renewal stickers had been sold, leaving 106,700 still to go.

Motorists with outstanding parking or traffic tickets must pay them off at the downtown office in the Municipal Center, 301 C St. NW, before receiving tag stickers. That office is open also for routine renewals from 8:15 a.m. to 4 p.m. Monday through Friday. Checks, money orders or cash are accepted.

Car owners who do not have completed, computerized application forms for their renewals may obtain them only at the Municipal Center, whether or not they immediately buy the tag sticker, Thompson said.

Three other renewal offices are open from 9:30 a.m. to 6 p.m. Monday through Friday for car owners who already have the proper application forms. They are at the Northeast inspection station, 1827 West Virginia Ave. NE; Carter Barron fringe parking lot, 16th and Kennedy streets NW, and the Fort Dupont ice skating rink, Ely Place between Minnesota Avenue and Ridge Road SE. Checks and money orders, but not cash, will be accepted at these locations.