The National Planning Policy Framework published on 17 August 2026 replaced the previous Framework and introduced a new structure for national planning policy. One of the provisions carried forward into the new Framework is a potentially significant change to the way some local planning authorities must calculate their five-year housing land supply.

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For some authorities, the additional buffer could affect their ability to demonstrate the required supply of deliverable housing sites, with important implications for planning applications and appeals.

Under Annex D of the August 2026 Framework, a five-year housing land supply must include a buffer brought forward from later in the plan period. The usual buffer is 5%, but this rises to 20% where the Housing Delivery Test shows significant under-delivery over the previous three years.

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For decision-making purposes, a 20% buffer also applies where an authority has a housing requirement adopted within the previous five years, examined against a version of the Framework published before December 2024, and its average annual housing requirement is 80% or less of its latest standard method local housing need figure. The same provision can apply where an older housing requirement has been reviewed and found not to require updating.

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Authorities that could previously demonstrate an adequate supply may therefore find that the additional buffer increases their housing land requirement to the point where they no longer meet the national policy test.

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It is too early to say how many councils will ultimately be affected. As authorities review their evidence and recalculate their housing land supply positions, the picture will become clearer. What is already apparent, however, is that some published housing land supply statements may no longer reflect the calculation required by the current Framework.

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For applicants and promoters, that means an authority’s published supply position should not automatically be accepted simply because it was accurate only a few months ago.

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The consequences of a housing supply shortfall must also now be understood through the revised decision-making structure. The August 2026 Framework no longer uses the former formulation under which the policies most important for determining an application were treated as out of date and the conventional “tilted balance” was engaged.

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Within settlements, Policy S4 states that development proposals should be approved unless the benefits would be substantially outweighed by adverse effects when assessed against the national decision-making policies. A housing supply shortfall can increase the weight given to the provision of additional homes, but it is not a separate gateway to that test.

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Outside settlements, Policy S5 expressly identifies development addressing an evidenced unmet need as one of the forms of development that may be supported. For housing, an unmet need exists where the authority cannot demonstrate a five-year supply of deliverable sites or scores below 75% in the most recent Housing Delivery Test. The development must also be physically well-related to an existing settlement and of a scale that can be accommodated, taking account of existing or proposed infrastructure.

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Different provisions apply to development in the Green Belt and on land designated as Local Green Space. A housing supply shortfall does not displace the national policies applying to those areas or guarantee that permission will be granted.

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Importantly, the authorities most affected may not be those that failed to plan for housing growth. Many adopted Local Plans were examined against earlier versions of national policy using housing requirements that were appropriate at the time. Comparing those requirements with current standard method housing need can now trigger a 20% buffer that was not anticipated when the plan was prepared.

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For developers, landowners and site promoters, this presents both a risk and an opportunity. Residential sites that previously appeared difficult to bring forward may warrant fresh consideration where an authority’s housing land supply position has weakened. Equally, planning strategies relying on a published five-year supply position should be reviewed to establish whether the calculation complies with Annex D of the current Framework.

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The changes reinforce the importance of scrutinising the evidence behind any claimed housing land supply. The relevant housing requirement, applicable buffer, deliverability of individual sites and date of the published evidence can all materially affect the calculation.

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The direction of travel is clear. The revised buffer has created a potential point of vulnerability for some local planning authorities while strengthening the housing benefit associated with suitable development where a compliant five-year supply cannot be demonstrated.

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A council’s housing land supply position may have changed, even if its published evidence has not.