In recent years a variety of charges, often referred to as exactions, have become part of the land development scene. Numerous communities have resorted to exactions, sometimes quite substantial, before giving permission to develop. In some cases they are required only if there is to be a rezoning or zoning variance. In other cases the exactions are charged for development within the existing zoning law. In general, the exaction is charged to pay the costs that the development is presumed to impose upon the community.
In some cases the exaction may be for a closely related cost; for example, nearby road construction needed to carry the additional traffic that new commercial development will generate, or school or park construction that the population of a new residential development will require. In other cases the connection may be more tenuous. For example, San Francisco decided that new office development increases the demand for housing in the city.
Since 1981 builders of office structures of over 50,000 square feet of floor space must earn housing credits by either building new units themselves or contributing funds to housing rehabilitation or affordable housing projects. The number of credits was based on estimates of how many square feet of office floor space are required per worker, what percentage of the San Francisco office workforce lives in the city, and how many workers live in the average housing unit.