Must office builder supply homes, too?

Developers that want to build offices in cities may have to help build homes for the workers, too. In some United States cities, developers of office complexes, high-rise or not, may be required by local governments to give parallel assistance in building or financing housing.

The idea developed in one city is based on the theory that downtown office space requires one employee for each 250 square feet of space. The theory in general then turns into a formula that says 40 percent of the employees-to-be will live within the city proper and will need housing. Although the concept is controversial, high-rise developers may have to lend their talents (and money) to put up housing facilities in addition to the contemplated office space.

Five or six other big cities are toying with ideas like this - especially since the Reagan administration has reduced many of the former government housing subsidies. While the program in some areas like San Francisco has stirred up much opposition and debate, it is not too different from what developers have long been required to do in the bargaining process surrounding public improvements. The ''donations'' often required of urban planners and developers have not only included street pavements, sewers, lighting, and parks, but in some cases schools and fire stations.

Critics of the build-offices-build-housing-also plan say it amounts to a new kind of permit fee based on area zoning.