The Government published the new National Planning Policy Framework (NPPF) on 17 August 2026. This followed consultation on the draft Framework issued in December 2025. The reforms include several important NPPF development viability changes.The revised NPPF supports the Government’s wider planning reform programme. It aims to create a faster, more certain planning system and increase housing delivery.
We have now had time to examine the new NPPF in detail. The NPPF development viability changes represent one area of particular interest to us.
NPPF Development Viability Changes: The Overall Direction
The overall approach remains firmly plan-led. Policy DM5 assumes that policy-compliant development will remain viable. However, the final wording offers more flexibility than the December 2025 draft. Applicants now have greater scope to justify a site-specific Financial Viability Assessment (FVA).
A couple of changes stand out.
A More Flexible Test for Site-Specific FVAs
The draft referred to development differing “significantly” from the typologies used during plan-making. It also required site characteristics to differ “substantially”. The final NPPF replaces both tests with the less restrictive phrase “materially different”.
How the NPPF Development Viability Changes Address Site-Specific Costs
Perhaps more importantly, the draft only considered costs that nobody could have foreseen during plan preparation. The final NPPF takes a different approach. It refers instead to costs that the development plan’s viability assessment did not consider. This distinction matters for sites facing abnormal or site-specific costs. The assumptions behind plan policy may not have adequately accounted for these costs.
Changes to Viability Review Mechanisms
The draft required decision-makers to consider viability review mechanisms when schemes offered contributions below policy requirements. The final wording of DM5 removes this specific requirement. However, the NPPF still allows authorities to introduce review mechanisms through the plan-making process.
What the Final Policy DM5 Means for Viability Challenges
This is not an open door to viability challenges. FVAs will still need to be robust, transparent and clearly demonstrate why a scheme differs from the assumptions made at plan-making stage. However, the final wording appears to provide a more pragmatic route for genuinely constrained schemes than was envisaged in the draft.
Expert Financial Viability Assessment Support
We have undertaken a significant number of FVAs for clients right across the South West this year and are well versed in the level of detail and supporting information expected by local planning authorities, together with the relevant requirements of national policy, Planning Practice Guidance and RICS guidance.
If viability is proving challenging for your scheme, get in touch with our development team today to discuss how we can assist.
