Changing a planning permission: what section 73B could mean for developers

Planning permissions rarely survive the development process unchanged. Detailed design evolves, procurement pressures emerge and market requirements shift. The difficulty is that a commercially sensible amendment is not always one that the existing permission can accommodate easily.

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That is why the anticipated introduction of section 73B matters.

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For now, applicants remain reliant on section 96A for non-material amendments, section 73 for changes to conditions, or a fresh planning application where neither route is sufficient. Section 73 can accommodate substantial changes in some circumstances, but it cannot be used to alter the operative description of development.

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The Court of Appeal’s decision in Test Valley Borough Council v Fiske confirmed that boundary. Conditions imposed through section 73 cannot materially conflict with the operative part of the original permission. Importantly, the Court did not impose a separate rule that section 73 amendments must be “minor”. The real question is whether the amended scheme remains consistent with what was actually permitted.

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Section 73B is intended to provide more flexibility. Once commenced, it should allow changes to both the description and conditions where the resulting permission would not be “substantially different” from the existing one.

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That could remove an awkward gap in the current system. A proposal may be too material for section 96A but unable to proceed under section 73 because the description itself needs to change. At present, that can mean a fresh application even where the underlying development remains broadly the same.

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But section 73B will not make amendment strategy straightforward.

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The phrase “substantially different” is undefined and will require judgement in the context of the existing permission and the planning effects of the change. A relatively small physical amendment may still cross an important policy threshold. Early applications are therefore likely to test the limits of the new provision.

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Nor will section 73B remove the separate risk created by overlapping permissions. Hillside Parks Ltd v Snowdonia National Park Authority remains relevant where implementing one permission makes lawful completion of another impossible. That issue can arise on relatively modest schemes as well as major developments.

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The practical lesson is that post-permission amendments should be treated as a consent-management exercise, not an administrative afterthought.

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Before choosing a route, applicants should audit the operative description, approved-plans condition, previous amendments, implementation deadlines, section 106 obligations and any CIL, environmental or biodiversity consequences. Where more than one permission exists, the implementation strategy also needs to be tested.

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For projects requiring a description change now, there is a real timing decision: consider whether a non-material change to the description can be made under section 96A alongside a section 73 application, submit a fresh application, redesign the amendment to remain within section 73, or wait for section 73B.

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As at 20 August 2026, section 73B has been enacted but is not yet in force. The Government confirmed in July that it had “not yet been implemented”, and the procedural regulations and guidance are still awaited.

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Section 73B should improve flexibility. But the commercial advantage will not simply come from having another amendment route available. It will come from knowing when that route is appropriate, whether the permission history remains coherent and whether the resulting consent can still be implemented with confidence.