Does a local plan have to match every SDS number exactly?

The test is general conformity, not identical wording. In London practice, local plans have been found non-conformant where they would undermine a strategic policy, not where they add local detail. SDS-era cases outside London have not yet built a body of decisions.

What if the SDS is still emerging?

PM15 footnote 21 says conformity with an emerging SDS should also be taken into consideration. How much weight it gets depends on how far the SDS has reached and whether an existing strategy already covers the area.

For residents and practitioners · Updated 20 September 2026 · As at 20 September 2026

What is general conformity?

General conformity is the legal and policy link between an adopted Spatial Development Strategy and the local plans beneath it. The local plan must follow the SDS on strategic matters. It does not have to copy it. NPPF policy PM15 makes conformity one of the soundness tests for local plans. How far a local plan may depart on a particular site or figure is not spelled out in a single statutory definition.

Where the test sits

MHCLG's February 2026 paper says local plans will have to be in general conformity with the relevant SDS. That is the policy consequence of the SDS being the strategic tier.

The August 2026 NPPF puts it in the examination tests. Policy PM15 says a sound local plan must be, among other things:

Conformity – the plan is in general conformity with any adopted spatial development strategy for the area.

A footnote adds that conformity with an emerging SDS should also be taken into consideration, depending on the stage of that SDS and whether an existing strategy already applies.

PM2 says local plans should set out a positive vision and spatial strategy which supports delivery of the SDS for their area.

What "general" is doing in the sentence

The SDS must not specify particular sites. The local plan must allocate them. So conformity cannot mean that every allocation is written in the SDS. It means the local plan should not undermine the SDS on the matters the SDS is allowed to decide: the pattern of growth, the housing apportionment, the broad locations, the strategic infrastructure and the environmental frame.

That leaves a grey belt (in the ordinary sense) around:

whether a local plan can add a large site that the SDS did not identify as a broad location
whether it can fall short of an apportioned housing figure if it claims constraints
how two SDS areas that overlap a national park should be read together

Those questions will be answered in examinations. This site will update when decisions exist.

Practical use

If you are responding to an SDS consultation, argue the strategic point (the broad location, the distribution, the infrastructure). If you are responding to a local plan, check first whether the issue is already settled by an adopted SDS. A site objection that contradicts an adopted SDS on a strategic matter is a conformity issue, not only a local one.

If you are writing a local plan, record how each strategic policy relates to the SDS. That record is what the examiner will look for under PM15(e).

Questions

Does a local plan have to match every SDS number exactly?: The test is general conformity, not identical wording. In London practice, local plans have been found non-conformant where they would undermine a strategic policy, not where they add local detail. SDS-era cases outside London have not yet built a body of decisions.
What if the SDS is still emerging?: PM15 footnote 21 says conformity with an emerging SDS should also be taken into consideration. How much weight it gets depends on how far the SDS has reached and whether an existing strategy already covers the area.

Sources

NPPF August 2026, policy PM15 (Examining local plans) — MHCLG, 17 August 2026
NPPF August 2026, policy PM2 (Local plans) — MHCLG, 17 August 2026
Areas for producing spatial development strategies (consultation paper) — MHCLG, 12 February 2026
Planning and Infrastructure Act 2025, inserted PCPA 2004 s.12D (contents) — legislation.gov.uk, 18 December 2025

SDS vs local plan — Basics
What is a Spatial Development Strategy? — Basics
How to respond to an SDS consultation — Participate