BNG what latest decisions mean

United Kingdom | 12 June 2026
Reading Time : 5 minutes

What’s been published

Defra has issued formal government responses confirming how BNG will be applied to NSIPs under the Planning Act 2008 and setting out refinements to the BNG regime for smaller and brownfield schemes. As of the 2 June the governments guidance has now been updated to implement them. These include changes to exemptions, thresholds and processes aimed at improving proportionality. Further secondary legislation and guidance are expected during 2026, alongside the outcome of a separate consultation on a potential targeted exemption for residential brownfield development, which has not yet concluded.¹

What’s confirmed

For NSIPs, the government has confirmed that mandatory BNG will apply to applications submitted on or after 2 November 2026, with a 10% net gain target aligned to the TCPA regime. BNG will be applied within a defined BNG project boundary rather than a DCO boundary, focusing on habitats that are negatively affected or used to deliver biodiversity gain. Importantly, on site and off site delivery are given equal weight, reflecting the strategic scale and complexity of nationally significant schemes.

Applicants will be required to submit an Outline Biodiversity Gain Plan at DCO application stage, with updated or phased plans provided ahead of construction. Spatial risk requirements for off site delivery are expected to move towards alignment with Local Nature Recovery Strategies. The government has also confirmed that mandatory BNG will not apply retrospectively to changes to DCOs that were consented before November 2026.

For smaller, medium and brownfield development, a new area based exemption of 0.2 hectares will apply, unless priority habitats are present. The existing self build and custom build exemption will be removed, and a series of new targeted exemptions are proposed, including for biodiversity enhancement schemes, temporary permissions of up to five years, and certain forms of development in parks, playing fields and public gardens.

Minor development remains within scope, with no blanket exemption introduced. However, the BNG hierarchy will be adjusted to make off site delivery easier to justify for these schemes. The statutory biodiversity metric will transition to a digital service, and further clarification is expected on the treatment of open mosaic habitat on brownfield land. Most of these changes are anticipated to come into force at the end of July 2026, subject to parliamentary scheduling.

What it means for your projects

BNG is now firmly embedded across both consenting regimes, but the way it applies will differ materially. For NSIPs, the confirmation of defined boundaries, clear submission stages and flexibility around delivery routes provides greater certainty. The approach of baselining only negatively impacted habitats, combined with an explicit acceptance of off site delivery, supports more proportionate and strategic biodiversity solutions.

For smaller and brownfield sites, the introduction of the 0.2 hectare exemption brings welcome proportionality, but it also places greater emphasis on early ecological screening. Where priority habitats are present, BNG obligations will still apply irrespective of site size.

Across all project types, the direction of travel is consistent: earlier ecological input, clearer governance, and stronger alignment between design, consenting and delivery will be essential to managing risk and cost.

Jonny Miller

Associate Director, Technical Lead – Strategic Biodiversity

United Kingdom

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Richard Brown

Associate Biodiversity Net Gain Consultant, BNG North and Midlands Lead, Nature

United Kingdom

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What to do now

Project teams should be confirming which BNG regime applies, when requirements will be triggered, and how this may influence site selection and scheme design from the earliest stages, including temporary land take decisions. For NSIPs, Biodiversity Gain Plans will need to be considered much earlier in the consenting programme. Exemptions should not be assumed until priority habitats have been confidently ruled out, and organisations should closely monitor forthcoming guidance on transitional arrangements, brownfield exemptions and metric changes.

How WSP can help

WSP supports clients across the full BNG lifecycle, from early strategy and feasibility through to delivery, monitoring and long term management. Our teams advise on BNG strategy for NSIP and TCPA projects, baseline surveys and habitat condition assessment, the preparation of outline, updated and phased Biodiversity Gain Plans, and the delivery of on site and off site solutions aligned with Local Nature Recovery Strategies. We continue to engage closely with emerging guidance and consultations to help clients stay ahead of regulatory change.

FAQs

When does BNG apply to NSIPs?

For NSIP applications submitted on or after 2 November 2026.

Which projects are in scope of BNG?

All NSIPs under the Planning Act 2008 and most TCPA developments, subject to confirmed exemptions.

What needs submitting, and when?

NSIPs must submit an Outline Biodiversity Gain Plan with the DCO application, followed by updated or phase plans before commencement. For TCPA applications, BNG is secured through a statutory pre-commencement condition, meaning key information is split between the planning application stage and a post-permission Biodiversity Gain Plan.

What area is assessed for BNG?

BNG applies within a defined BNG boundary, covering negatively impacted habitats and those used to deliver biodiversity gains.

Can BNG be delivered off site?

Yes. Off site delivery is permitted in both regimes and is given equal weight to on-site delivery for NSIPs and minor development.

Who approves the Biodiversity Gain Plan?

For NSIPs, the discharging authority may be the host planning authority, a lead authority or the Secretary of State, depending on the project. For TCPA developments, the Biodiversity Gain Plan is submitted post-permission to discharge the statutory biodiversity gain condition and is approved by the Local Planning Authority that granted planning permission.