Most development finance is priced and sized against a GDV built from private-sale values. When 20–40% of units must be sold at affordable or social-rent tenures — or delivered to a registered provider at a negotiated bulk price — the revenue assumption changes significantly. The finance structure changes with it. For a full overview of how we approach these schemes, see our affordable housing development finance page.
This article explains how development finance lenders assess affordable housing schemes, how grant funding from Homes England or the Greater London Authority slots into the capital stack, and what you need to know before you run the finance numbers on a scheme with an S106 obligation.
What counts as affordable housing for development finance purposes?
Affordable housing is a broad category covering several tenures, each with a different impact on GDV. Affordable rent (capped at up to 80% of market rent) and social rent (formula-linked, typically well below market) represent the lowest-revenue end. Shared ownership, First Homes (minimum 30% discount to market value), intermediate rent, and key worker housing sit at various points between market and heavily discounted. The tenure mix specified in a planning obligation determines how much of the scheme GDV is affected — and by how much.
Most schemes acquire an affordable housing requirement via a Section 106 planning obligation negotiated with the local planning authority as part of the planning permission. The tenure split, discount method, and delivery conditions are not standardised — they vary significantly between local authorities and individual planning agreements. Some schemes access capital grant from Homes England (via the Affordable Homes Programme) or the Greater London Authority (via the Mayor's London Affordable Homes Programme) specifically to fund the affordable units, reducing the shortfall between delivery cost and affordable tenure revenue. Each route carries different lender requirements and a different documentation burden.
How does affordable housing change the development finance calculation?
The fundamental change is GDV. Affordable units sell or rent at a discount to market. A scheme with 30% affordable units might see GDV fall by 10–15% relative to an equivalent all-private scheme, depending on the tenure mix and the registered provider's bulk purchase price. Delivery cost does not fall by the same amount — affordable units typically cost the same to build as private units, and sometimes more if a registered provider specification or Homes England grant requires specific standards. The gap between cost and affordable revenue is the affordable housing deficit, the part of the scheme that is cross-subsidised by private-sale profit.
This has direct consequences for the loan. Experienced development finance lenders model the affordable housing deficit explicitly. They will want to see the registered provider forward commitment — or a Homes England AHP allocation letter — before agreeing to include the affordable GDV in the appraisal. An uncommitted affordable housing obligation with no forward sale or grant in place is treated as a GDV risk, not a credit. A generalist lender unfamiliar with the tenure profile may decline or over-price simply because the GDV structure is unfamiliar; specialist lenders understand the market and model it correctly. For context on the broader range of development finance structures available, that overview covers where affordable housing schemes sit within the product landscape.
Where a scheme has a large affordable housing deficit and tight private-sale margins, overall LTGDV can compress — meaning a smaller maximum loan against the same build cost. The offset is that a well-structured scheme with a committed RSP and confirmed grant can be financed cleanly, because the lender has a clearer picture of the revenue position than on an all-speculative development.
Section 106 obligations and development finance
A Section 106 agreement is a legally binding contract between the developer and the local planning authority. It attaches to the planning permission and binds successors in title. An S106 affordable housing obligation typically specifies the number of units, the tenure mix, the discount method (for example, 70% of market value, or at social rent formula), and the conditions under which they must be delivered and transferred to a registered provider.
The lender's solicitor will review the S106 in full. Key items they look for: whether the obligation is fixed or contains a viability review mechanism (lenders generally prefer fixed obligations — a viability review introduces uncertainty around whether the affordable requirement will change during the build period); tenure and occupancy restrictions (do any units carry nomination agreements or grant conditions binding the title beyond the affordable tenure?); and trigger points (must affordable units be built first, or in proportion to the wider development?).
Some S106 agreements include cascade mechanisms — if the developer cannot sell affordable units to a registered provider within a defined period, the tenure may revert to open market. Others have no cascade and require delivery regardless of RSP demand. Lenders treat these differently, and the cascade structure can materially affect the downside scenario they underwrite against.
Where affordable units are phased differently from private units — a common requirement where affordable delivery is triggered early in the programme — this affects the loan drawdown and monitoring schedule. Map the delivery trigger points clearly before presenting to lenders. The phasing determines when your affordable GDV revenue arrives, which changes the cashflow the lender models against their facility.
Grant funding alongside development finance
Homes England's Affordable Homes Programme provides capital grant to fund affordable housing delivery. Grant is accessible to registered providers and to private developers who partner with an RSP or apply directly under the developer-delivery strand. Grant is paid against specific milestones — typically start on site and practical completion of the affordable units — not as a revolving facility. It cannot typically be drawn against to support the main development loan during construction; it arrives as a milestone payment.
The most common structure with Homes England grant: the development finance lender provides the main facility (senior debt against GDV, including affordable units at their RSP forward-sale value); the Homes England grant arrives at milestones and is applied to reduce the loan outstanding or to fund specific affordable unit costs. Some lenders require a formal grant assignment so that grant receipts flow directly to the loan account rather than to the developer's general account. This is standard on grant-stacked schemes and is worth agreeing at heads of terms to avoid a legal bottleneck later.
The Greater London Authority operates its own programme (under the Mayor's London Affordable Homes Programme) with similar mechanics but additional design and tenure requirements — including a minimum 50% social rent target in many priority areas. Lenders active in London affordable housing are familiar with GLA grant stacking; ensure any broker you appoint has placed GLA grant schemes before, as the documentation requirements differ from the Homes England route.
Timing is a known pressure point. Grant milestones are not always aligned with development loan drawdown requirements. Map the grant payment schedule against the loan facility at heads-of-terms stage. A cashflow gap between a build-cost drawdown and the next grant milestone is common, and there are bridging structures available against a confirmed grant receivable — but they need to be identified early, not discovered mid-build.
Grant conditions also carry risk. Homes England and GLA grants require affordable tenure for defined periods, nomination rights, and specific design standards. Breach of conditions can require grant repayment. Lenders will require warranties and protections against clawback as standard legal documentation on grant-stacked schemes. Allow 4–8 weeks longer than a standard development finance transaction for legal completion.
What lenders look for on affordable housing schemes
RSP credibility. If units are being forward-sold to a registered provider, the lender assesses the RSP's financial standing and the forward commitment documentation. A letter of intent is not sufficient — a legally binding agreement with clear payment obligations is the minimum. Some lenders will want to see the RSP's most recent accounts or Regulator of Social Housing gradings alongside the commitment.
Grant confirmation. An AHP allocation letter from Homes England (or GLA equivalent) is required before lenders will underwrite grant into the GDV calculation. An expected allocation or an application in progress is not bankable. This is the single most common point where a scheme needs more time before it is lender-ready — and the reason to involve a specialist broker early, because they can advise on what documentation Homes England needs and how to move the allocation to a formal letter quickly.
Viability and sensitivity. Lenders will stress-test what happens if the affordable housing grant falls through or the RSP renegotiates the bulk purchase price. The private-sale units must still support the loan in the downside scenario. Where the private-sale margin is already tight, the sensitivity analysis will determine how much of the affordable GDV the lender is prepared to underwrite without a confirmed forward commitment.
Track record on affordable delivery. Delivering affordable housing to RSP specification and Homes England compliance requirements is more demanding than private-sale delivery — there are additional design standards, handover documentation requirements, and post-completion sign-off processes. Lenders look for evidence that the developer or their project manager has done this before. First-time developers structuring an affordable scheme can mitigate by partnering with an experienced RSP from the outset, or by appointing a project manager with a specific affordable delivery track record.
Capital stack structure. Where the affordable housing deficit is significant and the scheme margin is compressed, some developers reach for mezzanine debt or a JV equity partner to fund the gap between what senior debt will advance and what the developer has available. Both options have a cost. See our guide to mezzanine finance for how the cost structure works, and our guide to JV development finance for when a profit-share structure makes more sense than additional debt. The choice is scheme-specific — the right structure depends on the affordable housing deficit, the scheme margin, and how much equity the developer wants to deploy.
What to do next
If your scheme carries an S106 obligation or you are considering applying for Homes England or GLA grant, get a specialist broker involved early — before you finalise the land price or commit to a GDV assumption. The affordable housing deficit and grant timing will affect the finance structure significantly, and the assumptions you build into the initial appraisal need to reflect the actual lender landscape for affordable housing schemes, not the standard all-private rate card. For a full overview of how we structure finance on these schemes, see our affordable housing development finance page.
Tell us about your scheme and the affordable housing obligation or grant position. We'll map the lenders and grant programmes relevant to your scheme and give you a clear picture of what finance is available.