The requirement for Biodiversity Net Gain (BNG) has become a statutory part of the UK planning system, with significant updates rolled out across 2024 and into 2025. Under the Environment Act, all major developments must now deliver a measurable uplift in biodiversity value, with smaller sites joining the scope from April 2024. This blog outlines the key facts surrounding the UK’s BNG legislation and the most important updates as we move through 2025.
What Is Biodiversity Net Gain?
BNG is a planning requirement that ensures new developments leave the natural environment in a better state than before. It applies to most developments under the Town and Country Planning Act and requires at least a 10% biodiversity gain compared to the pre-development biodiversity value of the site. This is measured using the Statutory Biodiversity Metric, a tool developed by DEFRA that assesses habitat types, their condition, distinctiveness, and location.
Developers must set out how they will meet BNG obligations in a Biodiversity Gain Plan, submitted alongside planning permission applications. This includes details on the pre-development biodiversity, the predicted post-development biodiversity value, and how any habitat loss will be offset.
Key Legislative Requirements in 2025
As of 2025, several core elements of the BNG framework are now fully operational:
- Major developments must comply with the 10% net gain rule, supported by a completed Biodiversity Gain Statement.
- Small site developments and minor developments are also within scope, assessed using the Small Sites Metric.
- Developers unable to deliver sufficient on-site habitat creation must secure off-site biodiversity units or consider buying statutory biodiversity credits as a last resort under the biodiversity gain hierarchy.
- All units used for off-site delivery must come from a registered biodiversity gain site, listed on the Biodiversity Gain Site Register maintained by Natural England.
- Planning authorities and responsible bodies may enforce BNG delivery through Section 106 agreements or conservation covenants.
2025 Updates to BNG Implementation
In 2025, BNG policy continues to be refined through updates to guidance, tools, and regulation. The most notable developments include:
- Improvements to the statutory biodiversity metric tool, providing clearer rules on priority habitats, irreplaceable habitats, and how to treat habitat enhancements adjacent to statutory protected sites.
- Greater alignment with Local Nature Recovery Strategies, ensuring that BNG delivery contributes to broader nature recovery efforts.
- Updates to guidance on environmental land management schemes to help landowners stack funding options while still satisfying the biodiversity gain objective and additionality requirements.
- Strengthened monitoring and enforcement mechanisms for on-site gains, off-site BNG, and habitat management over the mandatory 30+ year period.
On-site, Off-site, and Statutory Credits: Understanding Developer Options
Developers are expected to prioritise on-site habitat creation where feasible. However, due to constraints such as limited space, ecological suitability, or the nature of the proposed development, many must seek alternative delivery routes. These include:
- Off-site biodiversity gains via habitat banks or third-party gain sites.
- Purchasing biodiversity units from landowners offering off-site units through mechanisms like Civity’s landbank.
- As a final fallback, buying statutory biodiversity credits from the UK Government, with the funds used to secure long-term biodiversity enhancement projects.
Civity supports developers in sourcing compliant off-site biodiversity units and completing the relevant sections of their biodiversity gain plans. We do not assist with on-site delivery, nor do we register developer-controlled land as gain sites.
The Role of Local Planning Authorities and Natural England
Local Planning Authorities (LPAs) play a critical role in assessing biodiversity gain plans, approving planning permission applications, and overseeing compliance. They may also act as the Responsible Body in cases where a Section 106 agreement is used. Where conservation covenants are applied, designated responsible bodies will monitor compliance over the 30+ year term.
All registered biodiversity gain sites must be submitted to the Biodiversity Gain Site Register, a public record that ensures transparency and traceability in the BNG market.
Opportunities for Landowners and Land Managers
BNG legislation creates new income streams for land managers by incentivising long-term habitat creation, habitat retention, and ecological stewardship. Land used for own land gain sites must be managed under a formal Habitat Management and Monitoring Plan (HMMP) for at least 30 years and registered with Natural England.
At Civity, we work directly with landowners to assess site potential, design compliant schemes, and sell biodiversity units to developers. We handle legal documentation, engage with LPAs, and oversee ecological reporting throughout the term. Whether it’s pasture, grassland, orchards, or other suitable existing habitat, we help landowners unlock funding while delivering measurable biodiversity outcomes.
Looking Ahead: Assessing Progress and Addressing Concerns
2025 is a critical year for embedding biodiversity net gain requirements across all sectors of development and conservation. With increasing scrutiny on the effectiveness of BNG, stakeholders must continue to assess progress, address concerns, and ensure that environmental outcomes are robust, transparent, and genuinely beneficial.
BNG is not a licence to destroy, nor a shortcut to consent. Instead, it offers a clear, rule-based approach to integrating nature conservation into planning, ensuring that the biodiversity value of every development site is enhanced, not lost.
How Civity Can Help
We support both developers and landowners in meeting BNG obligations through compliant, transparent, and enforceable agreements. Our focus is on brokering units from high-integrity gain sites, supporting legal documentation, and aligning with all statutory requirements from the biodiversity metric to the biodiversity gain site register.
Conclusion
With the full rollout of BNG requirements and updated legislation in 2025, delivering net gain is no longer optional; it’s a legal obligation. By understanding the key facts and using the tools now in place, developers, planners, and landowners can ensure compliance while contributing meaningfully to nature recovery across England.
BNG isn’t just a planning hurdle; it’s a strategic opportunity to invest in resilient habitats, support rural economies, and improve the long-term health of our environment.
