Section 106 has been the backbone of England’s affordable housing supply for over three decades, but the mechanism connecting planning permission to occupied homes is breaking down. On 28 January 2026, the Ministry of Housing, Communities & Local Government (MHCLG) published its Policy statement: a roadmap for Section 106 delivery in England, formally acknowledging what Registered Providers (RPs), housebuilders and local planning authorities (LPAs) have been reporting for years: thousands of constructed or consented S106 units sit uncontracted and unsold, and the gap between planning permission and construction completion is widening rather than closing.
The numbers set out by the Home Builders Federation (HBF) and cited in the roadmap’s supporting commentary are stark. Roughly 900 S106 affordable units are already complete but remain without an RP buyer, with a further 8,500 in the pipeline or under construction expected to reach practical completion within twelve months.
Beyond that, more than 17,000 units that already have planning permission remain uncontracted. The HBF has also found that more than 700 residential sites have been delayed or stalled over the past three years specifically because developers could not secure an RP to take on the affordable element of the scheme.
Negotiation timelines compound the problem. Research cited in the roadmap found that the average S106 agreement took 515 days to conclude in 2024/25, and that this period has been lengthening year on year. Every day added to that negotiation is a day the scheme cannot proceed to construction, and every unit left uncontracted after the completion is a day it generates no rent, no service charge income, and no return on the capital already committed to acquiring it.
The roadmap and the wider commentary from sector bodies point to a consistent set of causes, and none of them originate at the planning committee stage. Grant funding through the Affordable Homes Programme typically needs to cover between 50% and 70% of an RP's purchase cost for a scheme to stack up; where grant rates fall short of that, RPs cannot commit regardless of how strong the underlying scheme is. Balance sheet capacity has tightened across the sector as a result of rent caps limiting income growth, construction cost inflation eroding development margins, and the capital demands of decarbonisation programmes, remediation of cladding defects, and compliance with Awaab's Law. Each of these pressures reduces the number of units an RP can realistically take on in any given year, independent of the quality or location of the scheme being offered.
The structural weakness this exposes is that S106 viability and tenure mix are typically fixed at the point a planning application is determined, often years before a scheme reaches practical completion. An RP’s capacity, funding position and strategic priorities can shift substantially in that window, but the agreement itself is not designed to flex with them. The results is a pipeline that looks healthy on a planning register and stalled in practice.
The roadmap sets out a two-track response. In the short term, it establishes a route for developers to demonstrate that no RP is willing to buy already-built or consented units, triggering a structured renegotiation process. Units must first be registered on the Homes England S106 Clearing Service, a database Homes England was tasked with building in December 2024. If no RP purchase materialises within a defined window, LPAs are expected to agree a Deed of Variation, generally completed within 12 weeks, allowing the tenure to shift toward an alternative affordable product or, as a last resort, private market sale or rent. Where a scheme reverts under this route but the affordable units are not practically completed by 1 December 2027, the roadmap provides for the scheme to revert to its original tenure mix. This emergency mechanism is explicitly time-limited and applies only to developments that already exist or will complete by the end of 2027.
On the structural side, the roadmap commits to a standardised S106 template for schemes under 50 dwellings, drafted by Town Legal LLP, intended to cut negotiation time and reduce inconsistency between LPAs. It also signals greater transparency in pricing, clearer build and design standards for affordable units, and a package of financial measures including expanded use of Right to Buy receipts, access to the Local Authority Housing Fund, a low-interest loan scheme administered through the National Housing Bank and the Greater London Authority, and exploration of RP consortia to pool purchasing capacity. A parallel National Planning Policy Framework consultation, open until 10 March 2026, pushes viability and affordable housing parameters to be agreed shortly after an application is submitted rather than left open through to determination.
The roadmap is candid about its own limits. Its immediate measures address the existing backlog rather than the conditions that created it, and sector commentary has been consistent in pointing out that process reform cannot substitute for adequate grand funding or RP balance sheet capacity. Standardising template and requiring earlier viability discussions will reduce negotiation friction, but a scheme with a viability gap that cannot be closed by grant will still stall, however quickly the paperwork moves. The roadmap treats speed and transparency as the primary constraints; for a meaningful share of stalled units, the primary constraint is finance.
RPs do not need to wait for the standardised template or the outcome of the NPPF consultation to change how they engage with S106. Three changes are available immediately; at the point an agreement is negotiated rather than after completion.
Where an RP's funding position, grant allocation and cost base are tested against a scheme before heads of terms are signed, rather than re-tested when the units are ready for handover, the risk of a late-stage refusal to purchase falls sharply. This means engaging planning and development teams with finance and asset management colleagues from the point an LPA opens S106 negotiations, not after a decision notice is issued.
A significant share of stalled units are stalled not because no RP exists, but because the RP originally identified at the planning stage no longer has capacity by completion. Building milestone reviews into S106 agreements — checkpoints at which developer, LPA and RP reconfirm capacity, funding and delivery timetable — allows a capacity gap to surface and be resolved months before completion, rather than at the point a unit is ready to register on the Clearing Service.
RPs with capacity constraints on a specific tenure or location are better served identifying that early and registering interest across a pipeline of sites than waiting for individual developers to approach them scheme by scheme. Pooling capacity with other RPs, as the roadmap encourages, also allows smaller providers to take on units that would exceed their individual balance sheet limits.
None of these measures require legislative change or await the outcome of a government consultation. They shift the point at which viability is tested from the end of the pipeline, where a stalled unit has already cost months of delay, to the beginning, where a funding or capacity gap can still be closed or the scheme redesigned around a realistic buyer. The roadmap gives the sector new tools for clearing an existing backlog; closing the gap permanently depends on RPs and LPAs using the tools they already have, earlier than they currently do.