Green Belt assessments

The Open consultation: National Planning Policy Framework: proposed reforms and other changes to the planning system published December 2025 refers to the (draft) National Planning Policy Framework: Plan-making and national decision-making policies also published December 2025. Annex E of this document discusses Green Belt assessment saying

Green Belt assessments should:

• Identify the location and appropriate scale of the area or areas to be assessed, and in doing so:
  • i. consider all Green Belt within the Plan area in the first instance;
  • ii. be broadly consistent with any Strategic Green Belt assessment in an adopted Spatial Development Strategy
  • iii. ensure assessment areas are small enough to enable variations in their contribution to the Green Belt purposes to be assessed;
  • iv. facilitate identifying areas of grey belt by subdividing areas into smaller assessment units where this is necessary; and
  • v. consider where it may be appropriate to vary the size of assessment areas based on local circumstances. For example, the assessment of smaller areas may be appropriate in certain places, such as around existing settlements or public transport hubs or corridors;
• Identify areas of grey belt land, as defined in GB2 (Assessing existing Green Belt land) by evaluating the contribution each assessment area makes to Green Belt purposes (a), (b), and (d) set out in GB2, as below:
  • (a) Check the unrestricted sprawl of large built-up areas;
  • (b) Prevent the merging of neighbouring towns;
  • (c) Assist in safeguarding the countryside from encroachment;
  • (d) Preserve the setting and special character of historic towns; and
  • (e) Assist urban regeneration by encouraging the recycling of derelict and other urban land.
• Identify whether the release or development of the assessment area(s) would fundamentally undermine the five Green Belt purposes (taken together) of the remaining Green Belt when considered over the plan area.
• When making judgements as to whether land is grey belt, authorities should consider the contribution that assessment areas make to Green Belt purposes (a), (b), and (d).

The guidance then goes into some detail to describe the purpose of the various considerations to be made which include:

• Purpose A – to check the unrestricted sprawl of large built-up areas
• Purpose B – to prevent neighbouring towns merging into one another
• Purpose D – to preserve the setting and special character of historic towns considered large built-up areas.

Further information can also be found under the guidance Green Belt: Advice on the role of the Green Belt in the planning system. This guidance explains how local planning authorities should assess Green Belt land to identify “grey belt” and use that in both plan making and decisions. Grey belt is Green Belt land that makes a weaker contribution to certain Green Belt purposes, but identifying it does not automatically mean it should be released for development or allocated in a plan. Decisions must still apply the full National Planning Policy Framework (NPPF), so Green Belt contribution is only one factor among wider policy considerations.

Authorities are expected to identify grey belt when reviewing Green Belt boundaries to meet housing or other needs, normally as part of preparing or updating local plans. They also need to decide, case by case, whether land is grey belt when determining planning applications in the Green Belt, because different NPPF tests apply to development on grey belt (for example those in paragraph 155). To do this properly, they should prepare a Green Belt assessment, usually at local or joint authority level, and check whether any existing assessments are still up to date.

The guidance sets out key steps for these assessments. Authorities must first define the areas to be assessed, then evaluate how strongly each area contributes to Green Belt purposes (a), (b) and (d), using specified criteria. They must then consider whether other nationally important protections listed in NPPF footnote 7 (such as designated environmental or heritage assets, excluding Green Belt itself) would give strong reasons to refuse or tightly restrict development in that area.

Using this information, authorities identify which parts of the Green Belt qualify as grey belt, and then consider whether releasing or developing any of these areas would “fundamentally undermine” the five Green Belt purposes when the remaining Green Belt is looked at across the whole plan area. Only if release does not fundamentally undermine those purposes, and the wider NPPF policies are satisfied, can development on grey belt land be considered potentially appropriate.

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