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We have been awash with planning updates as of late, from the revised NPPF and the National Scheme of Delegation to the latest announcements in the Autumn Budget. Lost amongst these headline reforms have been 3 important developments to the Biodiversity Net Gain (BNG) regime, each of which has the potential to influence how BNG is delivered, regulated and funded in practice.
Nationally Significant Infrastructure Projects (NSIPs)
The most recent, and perhaps most significant, update is the extension of mandatory BNG to NSIPs. From 2 November 2026, new NSIP applications requiring a Development Consent Order must deliver at least a 10% biodiversity net gain. The regime broadly aligns with the existing planning permission framework, although it has been adapted to reflect the unique characteristics of major infrastructure projects. Biodiversity gain is measured against a defined BNG boundary, focusing on habitats affected by development rather than the entire application site, and developers are required to submit an Outline Biodiversity Gain Plan as part of the DCO process.
This marks the completion of the phased rollout of mandatory BNG across England's planning system. Introduced through the Environment Act 2021, it has taken five years for the regime to be fully implemented across both planning applications and NSIPs. As the updates below show, however, the Government's tinkering with the regime is far from over.
Brownfield exemption
Following confirmation of the 0.2-hectare exemption for small developments earlier this summer, the Government consulted on whether additional relief should be provided for brownfield development. The consultation was driven by concerns that mandatory BNG requirements could undermine the viability of smaller brownfield regeneration schemes, although that position was disputed by a number of environmental organisations. In the 2026 Autumn Budget, the Government announced its intention to exempt residential brownfield developments of up to 1.5 hectares from mandatory BNG requirements, although the formal consultation response and implementation timetable are still awaited. The Budget stated that the measure is intended to "reduce costs and ensure the government's brownfield-first ambitions directly support the delivery of more homes".
The reforms aim to achieve a balance that facilitates housing and commercial development on previously developed sites, while still prioritising mandatory BNG requirements for projects that pose the most significant ecological impacts and have the highest potential for delivering biodiversity benefits. Whether that balance has been achieved will no doubt remain a point of debate, with supporters viewing the reforms as a pragmatic response to viability concerns and critics arguing that they represent a further erosion of the biodiversity gains expected from development.
NPPF 2026
The August 2026 NPPF restricts local authorities' ability to require BNG above the statutory 10% minimum. Policy N1(2) provides that:
In practice, this limits the ability of local planning authorities to apply blanket policies requiring biodiversity net gain in excess of the statutory minimum. The NPPF also makes clear that local policies should not impose BNG obligations on categories of development that are exempt from the statutory regime, and decision-makers are directed not to afford weight to non-compliant policies seeking biodiversity gains beyond the statutory framework.
This represents a significant shift towards a more standardised national approach to BNG and reflects the Government's broader desire for greater national consistency across the planning system. While developers are likely to welcome the increased certainty and consistency, some local authorities and environmental groups may view the changes as restricting local discretion and limiting the ability of planning authorities to pursue biodiversity gains beyond the statutory minimum.
For any queries regarding the BNG updates, please get in touch.
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