BNG For NSIPs: Government Response Confirms Go-live On 2 November 2026

Summary

• 10% biodiversity net gain (BNG) target and the BNG regime will apply to all nationally significant infrastructure project (NSIP) applications made on or after 2 November 2026.
• A "BNG boundary" may be smaller than the Order limits for the purposes of the calculation, meaning the 10% requirement applies only to the area actually impacted by the development.
• A clearer framework for temporary land has been provided: reinstatement of existing habitats is non-significant and does not need to be legally secured, whilst habitat creation and enhancement counted towards post-development biodiversity value must be secured.
• Applications must include an outline biodiversity gain plan which includes a BNG Boundary Plan drawing, and then phased/updated biodiversity gain plans will be required through construction and operation.
• Amendments to the Planning Act 2008, which enable BNG for NSIPs, are in force from 7 May 2026 in advance of go-live in November 2026 through the Environment Act 2021 (Commencement No 11) Regulations 2026 (SI 2026/492) with biodiversity gain statements to come.

Introduction

Defra has published its response to the consultation on BNG for NSIPs. The consultation received 260 responses from developers, consultancies, and statutory bodies, alongside over 10,000 responses submitted via an RSPB campaign.

Whilst some detail has been deferred to later guidance, the response is substantive and the updated Model Biodiversity Gain Statement Text for Nationally Significant Infrastructure Projects in Annex 1 of the Government Response has been updated to incorporate the responses to the feedback. The RSPB campaign supported BNG for NSIPs and called for a greater target than 10%.

1. The BNG boundary: a sensible decision

This is the most significant policy change in the government response, and is genuinely good news that makes sense for NSIP schemes.

Defra has confirmed that unimpacted habitats do not need to be included in the BNG baseline. The BNG boundary includes only habitats within the Order limits that are negatively impacted by the development (both temporary and permanent impacts) or used to contribute towards BNG. Defra considers that this balances requiring ambitious biodiversity outcomes whilst ensuring requirements remain proportionate to the scale of impact.

This is the right outcome for NSIPs and will be of particular significance for linear projects. Defra has confirmed it will provide guidance on how the BNG Boundary Plan should be prepared, including for scenarios such as horizontal directional drilling where below-ground infrastructure may not impact surface habitats.

2. Temporary land: welcome clarity

The treatment of temporarily acquired land has been one of the more complex issues in the NSIP BNG discussion. Defra recognises the difficulties with delivering BNG on land that a Development Consent Order (DCO) requires to be returned to its prior owner and reinstated to their satisfaction, especially where there are interactions with the compulsory acquisition regime. Its response differentiates between significant and non-significant gains.

The key distinction is:

• All on-site habitat creation and enhancement counted towards the post-development biodiversity value is “significant” and must be secured.
• Reinstatement of existing habitats (replacing a temporary loss of habitat with the same habitat type and condition) is “non-significant” and does not need to be legally secured.

This is a practical resolution that reflects the realities of infrastructure delivery. Where a construction compound temporarily impacts a field of improved grassland and is then restored, that restoration will count towards the metric without requiring a 30-year management obligation on land the developer will not own.

Further, the BNG Metric User Guide will be updated to recognise the longer construction timescales typical of major infrastructure projects. Specifically, the rule allowing habitats temporarily impacted and restored within two years to be counted as retained will be extended to five years but only for habitats of low and very low distinctiveness and only for NSIPs.

3. On-site or off-site: helpful flexibility

Defra has confirmed that NSIP developers will be able to deliver on-site or off-site gains in the first instance. This is a significant difference from the Town and Country Planning Act 1990 (TCPA) regime where developers are required to try to deliver gains on-site before looking for off-site options. For both NSIP and TCPA developments, statutory biodiversity credits are only available as a last resort.

In practice, for many NSIPs it will be possible and preferred to deliver the gains on-site, however this gives the option to deliver off-site if that is more appropriate for the project.

4. Phased biodiversity gain plans: practical flexibility

To address concerns about the burden of submitting fully developed biodiversity gain plans at the application stage, Defra has allowed for a phased approach. Applicants will be required to submit an outline biodiversity gain plan at the application stage. An updated or phased plan must then be submitted for approval prior to commencement (or each phase of development), with any final shortfall in gains to be calculated and secured before project operation.

This mirrors good practice in environmental assessment for complex infrastructure. It will be interesting to see how NSIPs of different types look to structure the relevant phasing plans and particularly those few schemes where the majority of loss is expected in the operational phase.

Defra has also allowed for flexibility on who can discharge post-consent biodiversity gain plans. This role may be fulfilled by any relevant planning authority or by the Secretary of State in consultation with relevant planning authorities.

5. Consistency across sectors: a level playing field

Defra has decided to apply a consistent BNG requirement across all NSIP types without exemptions or voluntary approaches. Whilst it considers that this will ensure simplicity and fairness across sectors, it does result in the BNG target being easier to achieve in some sectors than others.

Arguments were made for sector-specific treatment, particularly for linear and net-zero infrastructure projects. Defra’s priority to align with the TCPA regime is evident through the responses; they particularly note the importance of ensuring the availability of the off-site biodiversity market for NSIPs.

What comes next — and when

The timetable is tight. Statutory instruments and biodiversity gain statements for all NSIP types will be laid before Parliament this summer, with BNG going live for NSIPs in November 2026. We have started to see actions coming through as the Environment Act 2021 (Commencement No 11) Regulations 2026 (SI 2026/492) were published on 6 May 2026. An updated metric user guide with NSIP-specific detail and supporting guidance will also be published ahead of go-live.

It is worth noting that the mandatory BNG requirement will not apply to changes to DCOs where the initial application was not subject to mandatory BNG.

Conclusions

Defra has recognised some of the specific challenges faced by NSIPs in achieving BNG were the TCPA regime to be directly applied. Allowing for a BNG boundary to only include the impacted habitats is a major and pragmatic step and the temporary land framework is welcomed. The phased approach to biodiversity gain plan submission is sensible and proportionate.

In reality, NSIP developers have been grappling with BNG for the last few years and there is an evolving number of examples that can be drawn upon. The guidance will be welcomed by NSIP developers however, who have been progressing speculatively but can now more confidently comply with a more tailored regime. We will be monitoring developments closely as the statutory instruments and guidance are published over the coming months.

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