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24 August 2026
With the opportunity to adopt new supplementary planning documents now over and a new National Planning Policy Framework in force, local planning authorities face a fundamentally changed landscape. In this article, James Goldthorpe, Rachel Lee and Emily Knowles from our planning team consider the implications for local planning authorities seeking to secure developer contributions through section 106 agreements.
Introduced through the Planning and Compulsory Purchase Act 2004 (“PCPA 2004”), Supplementary Planning Documents (“SPDs”) have long been a valuable tool for local planning authorities seeking to explain, supplement, and apply local planning policy to specific sites and, often, borough/district wide, between local plan cycles. Developer contributions SPDs, in particular, have strengthened the hand of many authorities when negotiating section 106 agreements for the provision of affordable housing and infrastructure.
However, the transition to the new plan-making system marks the beginning of the end for SPDs. Under commencement regulations[1] published earlier this year new SPDs had to be formally adopted by 30 June 2026, and any extant SPD will cease to have effect when the old-system local plan to which it relates is revoked or replaced. For many authorities already embarking on plan-making under the new system, the day when SPDs become legacy documents may be upon us sooner than anticipated.
Section 15CC of the PCPA 2004 introduces a new category of statutory development plan document, replacing SPDs: a document known as a ‘supplementary plan’. Whilst these sound similar to SPDs, there are fundamental differences between the two in terms of scope, legal status, and the procedural path to adoption. These matters all need to be comprehensively understood by local authority planners.
Section 15CC(3) provides that supplementary plans may include policies relating to the amount, type, location, or timetable for development at ‘a specific site in their area or at two or more specific sites in their area which the authority consider to be nearby to each other’, as well as other policies for achieving planning objectives at those sites, or outlining the infrastructure or affordable housing requirements to which development at those sites would give rise. Unlike SPDs, supplementary plans will not generally provide a vehicle for district-wide policy guidance on thematic matters such as developer contributions or climate change mitigation/adaptation. The one exception is design, where section 15CC(3)(d) allows supplementary plans to include design requirements or codes applying throughout an authority’s area.
A further key difference pertains to legal status. SPDs have always sat outside the statutory development plan: useful, often influential, but lacking formal weight. Supplementary plans will occupy firmer ground. Once adopted, they will form part of the development plan and the section 38(6) duty will apply, meaning that planning applications must be determined in accordance with a supplementary plan unless material considerations indicate otherwise. This gives supplementary plans considerably greater force in decision-making than SPDs.
With this greater power comes a more rigorous procedure on the path to adoption. Under the new local plan-making regulations, authorities seeking to adopt supplementary plans will need to publish a notice of intention, consult for at least six weeks, and – unlike the procedure for SPDs – submit the plan for independent examination, albeit with scope for the examination to be conducted through written representations and statements in most cases.
Historically, SPDs have assisted LPAs in seeking to secure infrastructure contributions in two key ways: (1) providing site-specific guidance on infrastructure contributions for allocated sites; and (2) providing area-wide guidance for securing contributions – or other planning obligations – across an authority’s area as a matter of course, including for smaller unallocated sites. Due to their statutory scope, supplementary plans will not be able to provide borough/district-wide guidance except in relation to design, meaning the justification for developer contributions will need to be included in local plans. By virtue of their statutory definition, they will perform the former, site-specific function, albeit with more procedural steps before adoption, which may create policy gaps in the space between local plan and supplementary plan adoption.
In relation to this site-specific issue, recent case law offers some reassurance. In Trafford MBC v Secretary of State for Housing, Communities and Local Government [2026] EWHC 261 (Admin), a development site lay within a strategic allocation in the Places for Everyone Joint Development Plan Document 2024 (“JDP”). The developer argued on appeal that no infrastructure contribution could properly be required because the area-wide masterplan – which was required by the JDP to provide further guidance on apportionment – was still being developed. The High Court disagreed, overturning the Planning Inspector’s decision to allow the appeal. The Judge emphasised that it is the development plan itself – not its drafting history nor extrinsic materials – which forms the statutory policy basis for assessing the planning merits of a proposal. In this case, the policy of proportionate contribution was a plain, prominent, and clear aspect of the development plan, fundamental to its purpose, and that position was unaffected by the absence of the intended masterplan. Reassuringly for LPAs, the decision indicates that, provided development plan policies exist – even at a high level – making clear that infrastructure contributions are necessary for a site, those contributions should still be provided, even in the absence of a masterplan or supplementary guidance providing detail as to apportionment or value of contribution.
Notwithstanding this reassurance, the inability to bring forward SPDs providing area-wide guidance on developer contributions for smaller unallocated sites and piecemeal development remains a live and unresolved concern in a world without SPDs. LPAs will need to think carefully about how they draft new local plans to protect the ability to secure such contributions.
The transition away from SPDs presents both challenges and opportunities. Whilst the site-specific function of SPDs can be replicated through supplementary plans – with the added benefit of development plan status and greater weight in decision-making – authorities will need to allow for longer lead-in times and more rigorous procedural requirements. For area-wide matters, authorities must look to the development plan itself: clear, comprehensive local plan policies will be essential if LPAs are to maintain their negotiating position with developers on contributions for smaller sites and piecemeal development.
In this changing context, an up-to-date development plan has never been more important. The new National Planning Policy Framework, published on 17 August 2026, provides that development plan policies which are materially inconsistent with the national decision-making policies in the Framework should be given “very limited weight”. With outdated policies at risk of being sidelined, and no SPDs to plug gaps, authorities must ensure that their local plans contain clear policies aligned with the new Framework. When it comes to securing developer contributions, this is made abundantly clear in policy PM12 of the Framework itself, which provides that “[d]evelopment plans should, at the most appropriate level, set out the contributions expected from development to support the delivery of the plan”, and goes on to note that this should include “plan-wide policies”, “site-specific policies”, and “policies for different types or location of site or types of development”.
[1] Levelling-up and Regeneration Act 2023 (Commencement No. 11 and Saving and Transitional Provisions) Regulations 2026
The planning team at Sharpe Pritchard LLP has extensive experience advising local planning authorities on plan-making, including supporting local authorities promoting their local plans through independent examination. Our team also has a wealth of experience negotiating planning obligations for local planning authorities and helping in-house planning lawyers to navigate a rapidly shifting policy and legislative landscape.
If your authority is seeking to strengthen its development plan or navigate the transition to the new plan-making system, we would be delighted to assist.
This article is for general awareness only and does not constitute legal or professional advice. The law may have changed since this page was first published.
