What’s ahead for BNG: Government publishes responses to BNG consultations

The first consultation considered options for “improving the implementation of BNG for minor, medium and brownfield development”. The second focused on the “implementation of BNG for nationally significant infrastructure projects (NSIPs)”. 

BNG and NSIPs

The timetable for introducing BNG for NSIPs has been revised once again. When initially proposed, BNG for NSIPs was expected to come into effect from “late November 2025”. This was subsequently amended to being “in place” by May 2026. The latest position now pushes implementation back further.

Now it has been announced mandatory BNG will apply to all NSIP applications made on or after 2 November 2026.

There is also an important change to how biodiversity gains may be delivered for NSIPs. Rather than requiring on-site biodiversity gains to be fully exhausted before off-site options can be pursued, developers will be able to deliver biodiversity gains either on-site or off-site in the first instance, with the purchase of statutory biodiversity credits remaining a last resort.

Defra has indicated that it will lay the relevant statutory instruments in May 2026. Alongside this, it will publish an updated statutory biodiversity metric user guide, including new detail specific to NSIPs, and additional supporting guidance.

BNG and Small Sites

A new exemption from BNG will apply to sites of up to 0.2 hectares, provided that no on-site priority habitats are affected. The exemption will be assessed by reference to the application red line boundary.

The Government estimates that this change will exempt “around 50% of residential planning permissions”. It has justified the approach on proportionality grounds, stating that: “This means the smallest developments, where the cost and administrative burden is proportionately highest, will no longer need to deliver BNG.”

The Government explicitly acknowledges that this exemption will result in fewer biodiversity units being delivered in the short term, and that there may be a corresponding reduction in demand for off-site biodiversity units. The impacts of the exemption are explored more here. 

At the same time, the existing exemption for small‑scale self-build and custom build development will be removed, meaning such schemes will in future be subject to BNG unless they fall within another exemption.

These changes are expected to come into force before 31 July 2026.

Looking further ahead, the Government has confirmed that additional changes affecting minor development (defined as all development that is not “major development”) will be introduced later in 2026.

Similarly to NSIPs, for minor development, off-site biodiversity gains will be placed on an equal footing with on-site gains, amending the current preference for on-site delivery. 

The Government has also confirmed that the de minimis exemption is likely to be reformed, but not as part of the current legislative changes. Instead, this will be considered as part of a new consultation on residential brownfield development, which is currently open until 10 June 2026.

Other new exemptions and amendments

A number of further exemptions and technical amendments are proposed, including:

• Development whose primary objective is to conserve or enhance biodiversity. Defra has indicated it will work with stakeholders to develop an appropriate definition and accompanying guidance.
• Temporary planning permissions of up to five years, where the entire development is temporary. This exemption will not apply where on-site priority habitats are affected.
• Development enhancing parks, playing fields and public gardens, intended to support social and public health benefits. This will also not apply where priority habitats are affected and will not extend to playing pitches enclosed within a sports stadium.

The Government also plans to modernise BNG tools and processes. The statutory biodiversity metric is to be moved from its current Excel-based format to a digital service.

Separately, the approach to spatial risk will change. Rather than using local planning authority areas and national character area boundaries, spatial risk will be based on Local Nature Recovery Strategy areas (of which there are much fewer). This is intended to better align with local government reorganisation and to enable developers to source off-site units across a wider area without triggering spatial multipliers.

For brownfield developments containing open mosaic habitat, the Government is exploring more nuanced approaches to habitat assessment and compensation. This includes testing a new medium distinctiveness habitat type that could better reflect the varied habitats found on abandoned or derelict land.

What happens next?

Many of the headline changes will be delivered through secondary legislation expected before the summer recess, with further reforms following later in 2026. Practitioners should also be aware of the ongoing consultation on brownfield residential development, which closes on 10 June 2026, as this is likely to shape the next phase of BNG reform.