As outlined in the DCLG report, the role of the organizations involved in the delivery of affordable housing, decisions about the amount and types of affordable housing to be provided in individual proposals should reflect local housing need and individual site suitability, and be a matter for agreement between the parties. Local planning authorities and developers should be reasonably flexible in deciding the types of affordable housing most appropriate to a particular site. The objective should be to ensure that the affordable housing secured will contribute to satisfying local housing needs as demonstrated by a rigorous assessment.
The policy on planning and affordable housing is set out in more detail in DETR Circular 6/98: Planning and Affordable Housing. Where a local planning authority has decided that an element of affordable housing should be provided in development of a site, there is a presumption that such housing should be provided as part of the proposed development of the site. Failure to apply this policy could justify the refusal of planning permission.
A recent report commissioned by the Department for Communities and Local Government stated that: 'It is not hard to make a strong argument for social housing at sub-market rents' (LSE report, 'Ends and Means', 2007).
Affordable Housing means housing that has a sales price or rental amount that is within the means of a household that may occupy, middle-, moderate-, or low income housing. In simple words it is "decent quality" housing that low-income households (those whose income is below the poverty level or below 50 percent of the median income for their area) can afford to occupy without spending more than 30 percent of their income or those households with slightly higher incomes (50 to 80 percent of the median income) can similarly afford (Jeffrey & William, 2005).
In the case for dwelling units for sale, housing that is affordable means housing in which mortgage, amortization, taxes, insurance and condominium or association fees, if any, constitute no more than  percent of such gross annual household income for a household of the size which may occupy the unit in question