A planning obligation is a legal agreement attached to a planning permission that requires the provision of certain services or infrastructure that will make a planning proposal that would otherwise be unacceptable, acceptable in the eyes of the planning system. There are two types of planning obligation; section 106 agreements, and Community Infrastructure Levy. Local planning authorities can use section 106 agreements to require, for example, that a certain proportion of housing on a residential development is affordable. Section 106 agreements are negotiated on a case by case basis. Community Infrastructure Levy is a fixed amount of money that must be paid by a developer when they get planning permission. The amount paid is in proportion to the size of a proposed development, and will be set out in a document published by the local planning authority called the ‘charging schedule’. This money must then be used to provide necessary infrastructure at the site; for example a new public park, school or bus shelters.