What the Latest Biodiversity Net Gain Updates Mean for UK Developers 

The early evidence is encouraging; BNG is expected to prevent between 6,000 and 10,000 hectares of habitat loss each year, while also encouraging earlier, more nature‑led design decisions. For developers, this is increasingly translating into greater certainty, smoother planning journeys and fewer late‑stage design changes. 

Building on feedback from local authorities, developers and ecologists, government has now published a set of updates aimed at strengthening and streamlining how BNG works in practice. Here’s what developers need to know and how it may affect your projects. 

BNG for Nationally Significant Infrastructure Projects (NSIPs) 

A major development is the confirmation that BNG will become mandatory for Nationally Significant Infrastructure Projects from November 2026. 

What this means for infrastructure developers 

• More preparation time: The revised go‑live date gives promoters time to embed BNG into scheme design rather than retrofit it later. 
• A proportionate framework: BNG will apply only to habitats impacted by development, not the entire red‑line boundary. Temporary habitat impacts will be treated more flexibly. 
• More delivery options: On-site habitats (retained, enhanced or created) will count, and where needed developers can use registered off‑site gains or statutory biodiversity credits. 
• Greater certainty: Secondary legislation and final gain statements will lock in the new framework and timings, responding directly to developer feedback. 

Overall, this approach aims to ensure major infrastructure can come forward efficiently while delivering biodiversity improvements at meaningful scale. A crucial difference, however, is the requirement that developers must submit an Outline BNG Plan at the Development Consent Order application stage and use the statutory metric to secure habitats for at least 30 years. 

Simpler BNG for Small and Medium Developers 

Recognising the importance of SME developers in housing delivery, the government is introducing targeted changes to reduce cost and complexity for smaller schemes. 

Changes expected by July 2026 (subject to Parliament) 

• A new area‑based exemption for sites of 0.2 hectares or less. 
• Removal of the existing exemption for small self‑build and custom‑build schemes. 
• An exemption for temporary permissions for up to five years. 
• A revised gain hierarchy for minor development, treating off‑site gains as equal in preference to onsite habitat creation or enhancement. 

For many smaller schemes, this represents a significant reduction in administrative burden while maintaining environmental outcomes. 

Updates to the Biodiversity Metric 

Several technical changes to the statutory biodiversity metric are planned, with practical benefits for developers: 

• Spatial risk simplified by relying only on Local Nature Recovery Strategy (LNRS) areas. 
• Clearer treatment of urban habitats, including improved guidance for Open Mosaic Habitat and potential new urban habitat categories. 
• Use of proxy habitats where Open Mosaic units are unavailable. 
• A move from Excel‑based tools to a digital, integrated service, improving usability, particularly for SMEs. 
• Possible refinements to watercourse assessments, including a category for heavily modified channels. 

These updates are intended to reduce uncertainty, speed up assessments and improve consistency across projects. 

Transitional Arrangements and What to Do Now 

Updated guidance, application forms and gain plan templates will accompany these changes. Clear transitional arrangements will explain which rules apply to applications submitted as the new measures are phased in. 

Until then, existing BNG requirements remain in force, and developers should continue to follow current legislation and planning practice guidance. 

Looking Ahead: Brownfield Residential Exemption 

A new consultation is exploring a targeted BNG exemption for residential brownfield development, in line with the government’s brownfield‑first housing strategy. Developers are invited to comment on definitions, size thresholds and safeguards to minimise environmental harm. The consultation closes on 10th June 2026. 

What this means for developers 

Taken together, these updates aim to: 

• Increase certainty and predictability in planning. 
• Reduce cost and complexity, especially for small sites. 
• Encourage earlier integration of biodiversity into design. 
• Support housing and infrastructure delivery while embedding nature recovery. 

As BNG becomes more established, the direction of travel is clear, developments that plan for biodiversity early and proportionately are likely to move through the system more smoothly, delivering benefits for nature, communities and development viability alike.