Affordable housing in planning: what counts and why it matters

Affordable housing in planning terms means homes built to provide accommodation below market prices for people on modest incomes. It is a planning requirement that applies when developers build new residential schemes; councils use it to ensure mixed communities and to address local housing shortages. After reading this article, you will understand what affordable housing is, the different types developers provide, and how councils enforce the requirement on new developments.

The definition is specific: affordable housing is not simply cheaper than average for an area. It is a formal category in planning policy with minimum standards for affordability, ownership types and occupier income. When you see it mentioned in a planning application or local news about a development, the term covers several quite different models.

What makes a home "affordable" in planning policy

In planning, affordable housing has a technical meaning set out in national policy. A home qualifies only if it meets affordability requirements for the people who live in it — usually households earning up to the local median income — and remains affordable to future occupiers (not just the first residents). The affordability must persist; a one-off discount that ends after five years does not count.

Councils assess affordability by comparing the rent or purchase price to local wages and incomes. A home offered at full market rates, even in a lower-priced area, is not affordable housing in planning terms. The requirement typically applies to a percentage of homes on large new developments — most commonly between 20% and 40% of units, depending on what the local plan sets and whether the developer can prove the scheme would not be viable with more.

Social rent and intermediate housing: the two main categories

Affordable housing splits into two broad types: social rent and intermediate housing. Most schemes include both, in the proportions the local plan or the planning officer specifies.

Social rent means homes owned and let by a housing association or council at rents kept below 80% of the local market rent. This is the deepest level of affordability and serves the lowest-income households. A household with a modest wage or relying on state benefits can afford it. Social rented homes remain under affordable-housing control indefinitely — the tenant can stay on protected terms, and when they leave, the home goes to another eligible household on the same basis.

Intermediate housing sits between social rent and market price. It includes shared ownership (where a buyer owns a percentage stake in the property and pays rent on the council- or housing-association-owned share), discounted market sales (where homes sell at a set discount to market price), and intermediate rent (at rates higher than social rent but lower than the open market). Intermediate housing reaches households who earn too much to qualify for social rent but cannot afford to buy or rent at full market rates.

Why developers must provide affordable housing

Affordable housing requirements come from national planning policy and from councils' local plans. When a council's local plan identifies a need for affordable homes — which most do — developers applying for permission on residential schemes above a set threshold (often 10 or more units) must include an affordable percentage.

The requirement serves two aims. First, it spreads access to housing across income groups; without it, new developments would serve only buyers and renters at market rates, deepening inequality in many areas. Second, it meets local need identified in the council's housing strategy. Councils cannot build enough council homes themselves, so they use the planning system to require developers to contribute.

If a developer argues the requirement makes a scheme unviable, they can submit a viability assessment — an independent financial report showing the scheme would make losses or inadequate returns. Planning officers or an independent assessor review it; if it is accepted, the affordable percentage can be reduced or removed. This is why you sometimes see planning applications with lower or no affordable housing on large sites.

Who the affordable housing is for

Affordable housing goes to people who meet eligibility criteria set by the council, the housing association managing it, or the developer. Typically this includes local residents, key workers (teachers, nurses, care staff), people on the council's waiting list, and those who work or have family in the area. Income limits apply — households above a certain threshold cannot apply. The income thresholds vary by area and by the type of affordable housing.

Allocation processes differ. Some developments run a lottery among eligible applicants; others use the council's housing register, where applicants are already ranked by need. Some social rent homes are reserved for people with particular needs — such as older people or disabled households — based on the development's design or the council's priorities.

Shared ownership: buying a stake in the home

Shared ownership is the most common form of intermediate housing. In this model, the buyer purchases a stake in the property — typically 25% to 75% — and pays rent to the housing association on the remaining share. The rent does not pay down the ownership stake; the buyer and the association own their respective shares indefinitely, unless the buyer later buys more of the property (called staircasing).

For buyers, shared ownership removes the need for a large deposit (because they are buying only part of the property) and reduces the mortgage size. For councils and developers, it provides affordable home ownership without handing over the land or building. The housing association retains control of the wider development and can manage maintenance, service charges and the future occupancy of the property.

When a shared owner moves, they sell their stake (usually back to the housing association or on the open market, depending on the lease terms). The home then passes to another shared owner or is rented at social rent, keeping it in the affordable sector.

How affordable housing stays affordable over time

The key difference between affordable housing and a one-off discount is permanence. Planners call this long-term affordability — the requirement that homes remain affordable to future occupiers, not just initial residents.

For social rent and most shared ownership, this is built into the lease or the housing association's control. When a tenant leaves a social rent home, the next household takes it on the same affordable terms. When a shared owner sells, the property remains under affordable-housing restrictions. Councils use covenants — legal obligations written into the property's title — to enforce this. A covenant binds future owners and occupiers; if breached, the council can take action to restore the property's status.

Some schemes use covenants that expire — for instance, after 25 years. After expiry, the home may revert to the open market, though many councils and housing associations buy these properties to keep them affordable. The permanence of a development's affordable housing depends on the terms agreed in the original planning permission and the Section 106 agreement between the council and developer.

Challenges and viability

Developers sometimes argue that affordable-housing requirements are unviable — that meeting them would make the scheme unprofitable or cause it not to proceed at all. When this happens, the developer submits a viability assessment. An independent assessor reviews the scheme's costs, revenues and the market it faces. If the assessment is robust and shows genuine loss, the affordable requirement can be negotiated down.

This mechanism exists because overly demanding affordable quotas could suppress development and ultimately reduce the number of homes (including affordable homes) that get built. In practice, viability disputes are common and often contested; developers, councils and local communities frequently disagree on whether a reduction is justified.

Reading planning applications for affordable housing

When you read a planning application, affordable housing details appear in the supporting documents and the planning officer's report. Look for the "affordable housing statement" or similar — this states what percentage of units will be affordable, what types (social rent versus intermediate), the tenure mix (ownership proportions) and how the housing will be managed and allocated over time. It may also reference a Section 106 agreement draft, which sets out the legal terms binding the developer to deliver what they have promised.

If the application includes a viability assessment, the planning officer's report will discuss whether it has been accepted and what the outcome means for the affordable percentage. If the recommendation is to reduce affordable housing from the policy requirement, the officer will explain the reasoning.

Planning applications on reading a planning application will help you navigate the documents you find. You can also check Section 106 agreements to understand the legal mechanism that enforces affordable housing delivery.

Do it now

If you are following a new development near you, start understanding its affordable-housing commitment with these steps.

• Find the planning application online via your council's planning portal and read the affordable housing statement.
• Note the percentage and types: is it social rent, shared ownership, or a mix?
• Check the Section 106 draft or summary to see how the council will enforce delivery and over what period.
• Track whether the scheme remains on the permitted percentage or whether a later amendment reduces it.

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