Supplementary Plans and SPDs: what is the difference?

 

England now has two very different things with confusingly similar names: the old Supplementary Planning Document (SPD) and the new Supplementary Plan.

An SPD is guidance. It can be a material consideration, but it does not form part of the statutory development plan. A new-style Supplementary Plan is different: once adopted, it forms part of the development plan and carries development-plan status when applications and appeals are decided.

The distinction became particularly important in 2026. The final date for adopting a new SPD was 30 June 2026. Existing adopted SPDs did not simply disappear on 1 July, but they are now operating under transitional arrangements while authorities move to the new plan-making system.

This page explains what survives, what has changed and why you should check the title and legal status of a document before relying on it in a planning statement or planning decision.

 

The short answer: a Supplementary Plan is not an SPD

 

The names sound as though one has merely replaced the other. Legally, that is not what happened.

• Supplementary Planning Document (SPD): an old-system document which adds guidance to development-plan policies. It is not itself part of the development plan
• Supplementary Plan: a new-system statutory plan prepared under the Planning and Compulsory Purchase Act 2004 as amended by the Levelling-up and Regeneration Act 2023. Once adopted, it forms part of the development plan

That distinction affects weight. Section 38(6) gives the development plan its statutory starting-point status: decisions are made in accordance with the development plan unless material considerations indicate otherwise. An SPD may influence that exercise, but it is not one of the development-plan documents to which section 38(6) gives that status.

 

What is a Supplementary Planning Document?

 

SPDs belong to the legacy plan-making system. They were commonly used for subjects such as design guidance, parking standards, developer contributions and planning gain, affordable housing, conservation areas and detailed guidance for particular sites.

The important legal point is that an SPD does not create development-plan policy in its own right. It can explain or add detail to policies in an adopted local plan or other development-plan document, and it can be a material consideration when a planning application is determined, but it cannot be treated as though it has the same statutory status as the policy it supplements.

That matters whenever an SPD appears to go further than the underlying policy. The starting point should be the development-plan policy itself: what does it actually require, and is the SPD genuinely explaining that policy or trying to create a new test?

 

An SPD is guidance, but it cannot simply be ignored

 

The fact that an SPD is guidance rather than part of the development plan does not mean an officer can acknowledge it and then move on without applying it. If the guidance is a material consideration which has been put properly into the decision, the decision-maker must engage with what it actually says and decide what weight it should carry.

That point was reinforced in R (Bronwen Manby) v Mayor and Burgesses of the London Borough of Hackney [2026] EWHC 1543 (Admin). The case concerned a householder extension and Hackney’s SPD, including a 45-degree amenity guideline. The officer’s report referred to the guidance but did not decide whether the proposal complied with it or explain the significance of any departure. The High Court quashed the permission.

The judgment does not turn an SPD test into a binding rule. The court expressly recognised the difference between guidance and development-plan policy. A proposal can still be approved despite departing from an SPD where the planning judgment justifies it. What the authority cannot safely do is give the guidance lip service without doing the assessment.

This is especially important with familiar local design tools such as 45-degree or 25-degree daylight rules. They are normally local guidelines rather than national planning law. Their methodology varies between councils, and passing or failing one is not automatically decisive. But where the local guidance is relevant, the officer should apply it and explain the resulting planning judgment.

 

What happened to SPDs on 30 June 2026?

 

30 June 2026 was the final date on which a new SPD could be adopted in England. The old SPD route is now closed to new adoptions: an authority cannot adopt a new SPD after that date.

However, an SPD which had already been adopted did not automatically vanish on 1 July 2026. The Government’s transitional arrangements keep existing SPDs in force until the relevant planning authority adopts a new-style local plan or, where relevant, a new-style minerals and waste plan.

So in August 2026 you may still find a perfectly operative SPD on a council website. The correct question is not simply whether it was prepared under the old system, but:

• was it validly adopted before the cut-off?
• what adopted development-plan policy does it supplement?
• has the authority yet adopted the new-style plan which ends the transitional saving?
• is the guidance still relevant to the proposal and current policy context?

An SPD does not gain extra status merely because it survives the transition. It remains an SPD: potentially material, but not part of the development plan.

 

What is a new Supplementary Plan?

 

The new Supplementary Plan was created by the plan-making reforms in the Levelling-up and Regeneration Act 2023. New section 15CC of the Planning and Compulsory Purchase Act 2004 allows relevant plan-making authorities to prepare one or more Supplementary Plans.

The new document is deliberately more formal than an SPD. It is subject to public consultation and independent examination. Once adopted it takes effect as part of the development plan, rather than sitting alongside the plan as guidance.

Government material describes this as giving a Supplementary Plan the same decision-making weight as a local plan. In practical terms, that means you should read it as part of the statutory plan for the site, alongside any operative neighbourhood plan, strategic plan, local plan and minerals or waste policies that are relevant.

 

What can a Supplementary Plan cover?

 

A Supplementary Plan is powerful, but its scope is deliberately restricted so that it does not become a shortcut around preparing a proper local plan.

The August 2026 NPPF reinforces that limit through policy PM4: Supplementary Plans are for locally specific design standards or a quick response to unanticipated change affecting a site or nearby group of sites, and should not be used to subvert the role, vision or spatial strategy of the Local Plan or minerals and waste plan.

For a local planning authority, the legislation generally confines non-design Supplementary Plan policies to matters relating to a specific site or two or more nearby sites. That makes the route suitable for a site-specific planning framework, a regeneration opportunity, a masterplan or another issue which needs development-plan policy without waiting for the next full local-plan cycle.

Design is the important exception. Design matters can cover a wider area, allowing an authority-wide or other broad design code to be prepared as a Supplementary Plan. The 2023 Act’s explanatory material expressly identifies design codes as a major use for the new route.

The Mayor of London may prepare Supplementary Plans for design matters across Greater London. Minerals and waste planning authorities may also prepare Supplementary Plans within the subject matter permitted for their functions.

So a council cannot simply move every subject that might once have appeared in an SPD into a Supplementary Plan. Always check whether the subject matter and geographical scope are permitted by section 15CC.

 

Can a Supplementary Plan change a Local Plan policy?

 

Potentially, yes – and this is another major difference from an SPD.

The 2026 Regulations expressly deal with a Supplementary Plan containing a policy which the plan-making authority considers, in substance, supersedes another policy in the development plan. Where that happens, the Supplementary Plan must say so and identify the policy being superseded.

That does not give an authority unlimited freedom to rewrite its Local Plan through a Supplementary Plan. The new plan must still fall within the statutory scope of section 15CC, have regard to the relevant development plan, be in general conformity with an operative Spatial Development Strategy where one applies, undergo consultation and pass independent examination.

But it does underline the central point: a Supplementary Plan is development-plan policy, not merely explanatory guidance.

 

How is a Supplementary Plan prepared?

 

The procedure is shorter than the full new local-plan process, but it is still a statutory plan-making process. Policy PM16 of the August 2026 NPPF describes it as a streamlined preparation, consultation and examination process, with examination focused on the legal requirements and whether the authority has had regard to relevant national policy and guidance.

Broadly, the authority must:

1. Include it in the plan timetable. The timetable identifies the subject matter and geographical area or sites, together with the intended dates for preparation
2. Give notice of its intention to commence preparation.
3. Prepare the proposed plan and map. The Regulations require the relevant submission documents and supporting material
4. Consult. There must be at least one formal consultation and the consultation period must be no less than six weeks
5. Submit the plan for independent examination. The authority must submit the required compliance and consultation statements and supporting documents
6. Undergo examination. The normal model is written representations, although a hearing must be held where the examiner considers oral representations are needed for adequate examination or fairness
7. Respond to the examiner’s recommendations and adopt the plan. Once adopted, it becomes part of the development plan
8. Publish the adopted plan and required adoption material.

This is why describing a Supplementary Plan as a replacement SPD can be misleading. It replaces the old route in one sense, but the procedural safeguards and legal effect are much closer to statutory plan-making.

 

What happens to a Supplementary Plan when a new Local Plan is adopted?

 

Unlike the saved old SPDs, a new Supplementary Plan does not automatically fall away merely because a later new-style Local Plan is adopted.

The 2026 Regulations require a local planning authority preparing its Local Plan to produce a Supplementary Plans Statement where Supplementary Plans are already in effect. For each plan, the authority must say whether the new Local Plan covers the same matters and whether it intends the Supplementary Plan to:

• remain in effect after the Local Plan is adopted; or
• be revoked, wholly or where appropriate in part, following adoption

That is a useful practical check when reading a newly adopted Local Plan. Do not assume that every earlier Supplementary Plan has been swallowed by it: look for the authority’s Supplementary Plans Statement and subsequent revocation/adoption material.

 

Why the distinction matters for a planning application

 

If a council cites a document against your proposal, first identify what it actually is.

If it is an adopted Supplementary Plan, it forms part of the development plan and should be addressed as such. If it is an SPD, it may still be a material consideration during the transition, but it does not acquire development-plan status merely because the council regards it as important.

This also has a practical link to planning application validation requirements. Policy DM2 of the August 2026 NPPF says additional local information requirements should be included where a development-plan policy requires a specific further assessment. An adopted Supplementary Plan can provide such a development-plan policy. An old SPD, being outside the development plan, cannot by itself supply that particular DM2 development-plan-policy basis.

That does not mean an SPD can never be relevant to the information supporting an application: statutory requirements, another development-plan policy and the facts of the proposal may still justify evidence. It means the legal and policy basis should be identified correctly.

 

Supplementary Plans, design codes and planning decisions

 

Design codes are likely to be one of the most visible uses of Supplementary Plans because design policies are allowed to operate across a wider area than the normal site-specific Supplementary Plan route.

For an applicant, this means a future authority-wide design code may have a very different status from the design SPD you are used to reading today. If adopted as a Supplementary Plan, it will form part of the development plan and should be dealt with directly in the planning case.

Check the adoption date and the document’s legal basis rather than relying on its appearance. A polished PDF headed design guide might be an old SPD, informal guidance or a statutory Supplementary Plan – and those are not interchangeable.

 

Do not confuse national decision-making policy with statutory NDMPs

 

The legislation creating Supplementary Plans contains references to future statutory National Development Management Policies. That regime should not be confused with the national decision-making policies in the August 2026 NPPF.

The current NPPF remains national planning policy and an important material consideration. The statutory NDMP provisions are a separate legal regime and have not been brought into operation merely by the publication of the August 2026 Framework. Our development plan guide explains the current hierarchy.

 

Practical checklist: SPD or Supplementary Plan?

 

• Check the exact title. Do not assume Supplementary means the same legal status
• Check the adoption date. A new SPD could not be adopted after 30 June 2026
• Check the authority’s adoption statement. A Supplementary Plan should have gone through the new statutory process and independent examination
• Check what the document covers. Non-design Supplementary Plans are generally site-specific or for nearby sites
• Check the development plan. An adopted Supplementary Plan is part of it; an SPD is not
• Check whether a new Local Plan has been adopted. That can end the transitional life of an old SPD
• For a new Supplementary Plan, check the later Supplementary Plans Statement. It should tell you whether the authority intends the plan to remain or be revoked when a later Local Plan is adopted
• For an application or appeal, give the document the right weight. Do not elevate guidance into policy or downgrade statutory policy into guidance

 

Costs, refusals and challenging a plan

 

There is no separate fee for reading or relying on an SPD or Supplementary Plan. Any planning application fee depends on the route being used, so check our planning fees page. Professional advice, planning statements and technical evidence may involve separate costs.

If an application is refused, the applicant will normally have a right of appeal. Whether the council relied on an SPD or a statutory Supplementary Plan can be important to the weight of the policy case. See our planning appeals section and check the relevant deadline early.

There is no ordinary planning appeal against the adoption of a Supplementary Plan. Its adoption statement must explain the separate High Court challenge route under section 113 of the Planning and Compulsory Purchase Act 2004, including the grounds and time limit.

 

Where to go next

 

Start with our guide to the development plan if you need to identify which statutory documents apply to a site. For the main council-wide plan, see Local Plans; for very local community policies, see Neighbourhood Plans.

If you are preparing an application, our guide to Planning Statements explains how to deal with the development plan and other material considerations in the planning case, while Validation Requirements covers what a council can lawfully and properly ask you to submit.

 

Relevant legislation and Government guidance

 

The new plan-making system is recent and the transitional provisions matter. The primary sources below should be checked for the current position.

• Planning and Compulsory Purchase Act 2004, section 15CC – statutory basis and permitted scope of Supplementary Plans;
• Planning and Compulsory Purchase Act 2004, section 15DB – independent examination of Supplementary Plans;
• Planning and Compulsory Purchase Act 2004, section 15EA – adoption of Local Plans and Supplementary Plans;
• Town and Country Planning (Local Planning) (England) Regulations 2026 – detailed new-system procedure, including regulations 6, 29 and Part 6;
• Levelling-up and Regeneration Act 2023 (Commencement No. 11 and Saving and Transitional Provisions) Regulations 2026 – commencement and transitional treatment of legacy plan-making and SPDs;
• Government plan-making regulations explainer – overview of Supplementary Plans and the SPD transition;
• Create or update a Local Plan using the new system – current Government implementation guidance;
• Creating a plan timetable – current requirements for including Supplementary Plans in the plan timetable

Other Planning Policy Sections

 

Supplementary Plans Page Updated: 27th August 2026