Biodiversity Net Gain: what's changing and what it means for you

Over the past two years, Biodiversity Net Gain (BNG) has started to change the way development and nature work together, and we’ve learned a huge amount from local authorities, developers and ecologists along the way.

The positive effects are already becoming clear, with BNG set to prevent between 6,000 and 10,000 hectares of habitat loss annually - an area roughly the size of Nottingham - and to prompt earlier, more nature-led design decisions. Together, these changes are embedding nature recovery into the development process and creating more sustainable, resilient places – a win-win for housing, infrastructure and the environment. This supports growth by providing greater certainty, reducing late-stage redesign, and helping development come forward more smoothly.

Building on these insights, we have published a set of key updates that strengthen and streamline how BNG operates across the planning system.

Firstly, our responses to the consultations on improving the implementation of biodiversity net gain for minor, medium and brownfield development and on implementing BNG for nationally significant infrastructure projects (NSIPs). Extending BNG to major infrastructure projects marks a significant step forward in delivering for nature while supporting growth and investment in critical infrastructure. Alongside this, we have also launched a new consultation on a targeted exemption for residential brownfield sites.

In this post, we summarise the key outcomes of the consultations, including technical updates about how and when these changes will be introduced.

Delivering on your feedback

We would like to thank all stakeholders who responded to the consultations.

The volume and detail of responses demonstrate the strong interest in BNG and reflect the wide range of expertise involved in delivering it. The decisions taken reflect a pragmatic balance between simplifying the planning system and ensuring BNG continues to contribute to nature recovery.

Introducing BNG for Nationally Significant Infrastructure Projects

As part of this package, we’ve confirmed how BNG will apply to Nationally Significant Infrastructure Projects (NSIPs) from November 2026. These include major transport, energy and water projects that are critical to economic growth and national resilience. We have adjusted the go-live date so that developers have sufficient preparation time to integrate the final framework into their scheme designs. This approach will support a smooth transition from voluntary practice to the mandatory framework.

Developers were clear they are committed to delivering BNG but need clarity and sufficient time to prepare. We will shortly lay the necessary secondary legislation and final gain statements to formally secure the revised implementation date, giving developers the certainty they requested through the consultation.

Bringing BNG into the NSIP system is an important next step for nature. It will ensure that much-needed major infrastructure is delivered while also protecting and restoring nature at scale. In line with the recommendations in the Nuclear Regulatory Review 2025, we are introducing a streamlined framework for NSIPs. Crucially, it applies only to habitats impacted by development, rather than the entire development site, and introduces measures to simplify the approach where impacts on habitats are temporary. Habitats retained, enhanced or created onsite can be included in calculations, and count towards BNG outcomes.

This revised approach balances ambitious biodiversity outcomes whilst ensuring requirements are proportionate and easy for developers to implement. Once BNG becomes mandatory, NSIPs will benefit from being able to use the full range of delivery options, including registered off-site gains and statutory biodiversity credits where needed.

Supporting guidance will be published to provide clarity and certainty about how BNG should be applied in the NSIP context.

Supporting SME developers with targeted changes

We’re also making BNG simpler and more practical for smaller developers, recognising their vital role in delivering housing and local growth.

In December, we announced a new exemption for sites of 0.2 hectares or below. Building on this, the government response sets out further targeted updates to exemptions, the biodiversity gain hierarchy, and the statutory biodiversity metric. These changes aim to reduce administrative burdens and improve flexibility for minor developments while supporting the continued growth of the BNG market.

These changes will be introduced in phases.

By the end of July 2026, subject to parliamentary scheduling, we expect to:

1. Introduce the new 0.2ha area-based exemption.
2. Remove the existing exemption for small scale self-build and custom-build development.
3. Exempt temporary planning permissions granted for a maximum of five years.
4. Amend the biodiversity gain hierarchy for minor development so that offsite biodiversity gains are given the same preference as onsite habitat creation or enhancement.

Later in 2026, we expect to:

1. Introduce an exemption for development whose primary objective is to conserve or enhance biodiversity.
2. Introduce a targeted exemption for development that enhances parks, playing fields and public gardens.

We will also make some changes to the statutory biodiversity metric, including:  

1. Adjust the way spatial risk is assessed for area habitats, using Local Nature Recovery Strategy areas only.
2. Improve identification of Open Mosaic Habitat (OMH) and other urban habitats by updating metric guidance, clarifying habitat definitions, and reviewing condition assessment sheets (including exploring a new medium distinctiveness urban habitat type).
3. Introduce the use of a proxy habitat as an acceptable alternative when no OMH units are available.
4. Move the current Excel metric tools to a digital, integrated service to improve usability and accessibility – especially for small developers.
5. Consider changes to the assessment of watercourse condition, including a new distinctiveness category for heavily modified watercourses.

We anticipate that the use of the de minimis exemption will be significantly reduced following the introduction of the new area-based exemption. Any changes to this exemption will be considered alongside the government response to the consultation on BNG for residential brownfield development. The existing guidance continues to apply, including the planning practice guidance that sets out what evidence requirements may be required when using the de minimis exemption.

Guidance and transitional arrangements

To accompany any legislative changes to exemptions and the biodiversity gain hierarchy, we will review and update guidance, planning application forms and gain plan templates where necessary.

We will also set out guidance on transitional arrangements. This will explain how to handle applications submitted during the period in which the new measures are being phased in, providing clarity to local authorities and developers on the requirements at each stage. Transitionary arrangements will also be put in place for any changes to the statutory biodiversity metric, including when moving the metric tools to a digital service.

Until changes take effect, the current BNG requirement remains in place and developers should continue to follow existing guidance and legislation when delivering BNG.

Exploring a potential BNG exemption for residential brownfield development

We have also launched a new consultation on an additional targeted exemption for brownfield residential development. This supports the government’s brownfield first approach and wider ambition to accelerate housing delivery on well-connected urban land. We are seeking views on the definition of brownfield residential development, potential size thresholds for any exemption, and measures to ensure any exemption is designed to minimise negative environmental impacts.

The Consultation will close on 23:59 on the 10 June 2026. If you would like to share your views, please visit Citizen Space.

Government remains committed to BNG

Collectively, these updates mark important evolution in BNG. While the scale of change is not insignificant, once fully embedded they will provide the clarity and stability needed to allow the BNG community to keep delivering development with nature at its heart.

We will continue to share updates as implementation progresses, helping stakeholders plan with confidence.