Last updated: June 26, 2026
Quick Answer: Mandatory biodiversity net gain for Nationally Significant Infrastructure Projects goes live on 2 November 2026, applying to all DCO applications submitted on or after that date. In early June 2026, the government laid ten biodiversity gain statements before Parliament, one for each NSIP category, confirming that all applicants must deliver at least 10% net gain. Ecologists and developers with live or forthcoming NSIP applications need to act now on baseline surveys, metric calculations, and biodiversity gain plans.
Key Takeaways
- Mandatory BNG for NSIPs applies to all Development Consent Order applications submitted on or after 2 November 2026. [1]
- Ten biodiversity gain statements were laid before Parliament in early June 2026, covering every NSIP category including energy, transport, and water. [2]
- All NSIP applicants must achieve a minimum 10% biodiversity net gain, consistent across all project types. [3]
- An outline biodiversity gain plan must accompany the DCO application; updated or phased plans follow before commencement. [4]
- The BNG boundary covers only habitats within the Order limits that are negatively impacted or used to deliver gain — unimpacted habitats are excluded from the baseline. [4]
- The 30-year habitat management and monitoring obligation applies to all secured gains, whether on-site, off-site, or via statutory credits.
- A separate consultation on small-site thresholds (including a proposed 0.2 ha exemption) closed on 10 June 2026 — this is entirely distinct from the NSIP regime and does not affect it.
- Ecologists should begin pre-application baseline surveys immediately for any NSIP project targeting a 2026 or 2027 DCO submission.
What Is Mandatory BNG for NSIPs? The Regime Explained
Mandatory BNG for NSIPs is a statutory requirement under the Planning Act 2008, as amended, compelling all NSIP applicants to demonstrate that their project will leave biodiversity measurably better off than before development. The mandatory BNG NSIPs 2 November 2026 start date means any DCO application received by the Planning Inspectorate on or after that date must comply in full. [1]
Unlike the Town and Country Planning Act regime (which has applied to most major planning permissions since early 2024), NSIPs follow a separate consenting pathway through the Development Consent Order process. The ten biodiversity gain statements published in June 2026 set out how BNG is calculated, delivered, and reported within that pathway, providing the clarity that NSIP promoters have been waiting for. [2]
For a broader grounding in how the BNG framework operates, see this biodiversity net gain explained guide.
How Do Biodiversity Gain Statements Work?
Each of the ten biodiversity gain statements corresponds to a specific NSIP category — energy, highways, railways, airports, water resources, waste water, hazardous waste, and others. Together they confirm the framework and reporting requirements for calculating and delivering BNG across every NSIP type. [2]
Key mechanics established by the statements include:
- Baseline assessment: Habitats within the Order limits that are negatively impacted must be assessed using the Biodiversity Metric. Unimpacted habitats do not need to be included, which simplifies baseline scoping for large linear infrastructure. [4]
- 10% net gain target: The uniform requirement applies regardless of project type or scale. [3]
- Outline biodiversity gain plan at application: Applicants submit an outline plan with the DCO application. Detailed or phased plans are then submitted for approval before commencement or each phase. [4]
- Temporary land: Reinstatement of existing habitats on temporarily acquired land is treated as non-significant and does not need to be legally secured. Any habitat creation or enhancement counted towards post-development biodiversity value must be secured. [4]
- Shortfall resolution: Any final shortfall in gains must be calculated and secured before the project enters operation. [4]
What Changed in the June 2026 BNG Update?
The June 2026 update delivered two distinct regulatory developments — and it is important not to conflate them.
First: Defra laid the ten biodiversity gain statements before Parliament on 4 June 2026, confirming the operational framework for NSIP BNG. This was the single most significant step in readying the NSIP regime for the 2 November 2026 go-live. Alongside the statements, Defra published detailed guidance documents covering calculation methodology, delivery options, and reporting obligations. [2]
Second, and separately: A consultation on proposed changes to BNG thresholds for Town and Country Planning Act development closed on 10 June 2026. One proposal under that consultation would exempt sites of 0.2 hectares or below from mandatory BNG requirements — though any such sites would remain subject to NPPF policies and wider regulatory protections. This consultation is entirely separate from the NSIP regime. The 0.2 ha threshold, if adopted, would not apply to NSIPs, which operate under the Planning Act 2008 and the biodiversity gain statements framework.
When Does Mandatory BNG Start and Who Must Comply?
Mandatory BNG for NSIPs starts on 2 November 2026. Any DCO application submitted to the Planning Inspectorate on or after that date must include a biodiversity gain plan and demonstrate compliance with the relevant biodiversity gain statement. [1]
Who is in scope:
- All NSIP promoters submitting DCO applications from 2 November 2026 onwards, covering energy generation and transmission, strategic road and rail, airports, harbours, water and waste water infrastructure, and other nationally significant projects.
Who is not directly affected by the NSIP regime:
- Developers pursuing consent under the Town and Country Planning Act (they follow the existing mandatory BNG regime that has applied since 2024).
- Projects that obtained DCO consent before 2 November 2026.
Legal analysis confirms that BNG is expected to form a substantive part of the examination process for DCO applications going forward. [3]
How Do Developers Calculate Biodiversity Net Gain for NSIPs?
Developers calculate BNG using the statutory Biodiversity Metric, comparing pre-development habitat condition and extent against post-development outcomes. The calculation must show at least 10% net gain. [3]
Step-by-step process for NSIP projects:
- Define the BNG boundary — habitats within the Order limits that are impacted or used to deliver gain. [4]
- Commission pre-application baseline habitat surveys (Phase 1 and, where required, Phase 2).
- Run the Biodiversity Metric to establish the pre-development biodiversity unit value.
- Design on-site habitat creation and enhancement to maximise gain within the project footprint.
- Identify off-site habitat delivery or statutory biodiversity credits to cover any remaining shortfall.
- Prepare the outline biodiversity gain plan for submission with the DCO application.
- Submit updated or phased plans before commencement of each phase.
- Secure all gains legally (management agreements, conservation covenants, or equivalent) for a minimum of 30 years.
For guidance on the on-site versus off-site decision, see biodiversity net gain: off-site or on-site delivery. If off-site units are needed, the guide to biodiversity credits for developers covers procurement options.
What Do Ecologists Need to Do for BNG Assessments on NSIPs?
Ecologists are central to every stage of NSIP BNG compliance. For the mandatory BNG NSIPs 2 November 2026 regime, the core professional responsibilities are:
- Pre-application baseline surveys: Habitat surveys must be carried out at the right time of year for the habitats present. For large linear projects, this means early programme planning to avoid survey season conflicts. A full biodiversity net gain assessment will be required.
- Metric calculations: Ecologists must apply the statutory Biodiversity Metric correctly, including condition assessments for each habitat parcel within the BNG boundary.
- Biodiversity gain plan preparation: Ecologists draft and review the outline plan submitted with the DCO application, and subsequent phased plans.
- Monitoring plans: A 30-year monitoring programme must be designed, specifying survey intervals, success criteria, and adaptive management triggers.
- Reporting: Ongoing reporting obligations run for the full 30-year management period.
"The publication of biodiversity gain statements provides much-needed clarity for NSIP promoters, allowing them to progress applications with confidence." — BCLP Law analysis, 2026 [3]
How Is BNG Different from Traditional Environmental Impact Assessment?
BNG and Environmental Impact Assessment (EIA) are complementary but distinct. EIA identifies, describes, and assesses the likely significant effects of a project on the environment — it is largely a disclosure and mitigation exercise. BNG goes further by requiring a measurable, legally secured net positive outcome for biodiversity specifically.
| Feature | EIA / Habitats Regulations | Mandatory BNG |
|---|---|---|
| Purpose | Assess and disclose impacts | Deliver measurable net gain |
| Outcome | Mitigation of harm | Minimum 10% improvement |
| Legal security | Conditions and obligations | 30-year secured management |
| Metric | Qualitative and quantitative | Statutory Biodiversity Metric |
| Reporting | At consent stage | Ongoing for 30 years |
BNG does not replace EIA or Habitats Regulations Assessment. All three apply in parallel to NSIP projects.
Can Developers Get Exemptions from Mandatory BNG for NSIPs?
There are no broad exemptions from mandatory BNG for NSIP projects submitted on or after 2 November 2026. The 10% net gain requirement is uniform across all NSIP categories. [3]
The proposed 0.2 ha small-site exemption under the separate June 2026 consultation applies only to Town and Country Planning Act development, not to NSIPs. Developers should not assume that threshold will carry across.
Certain specific treatments exist within the NSIP framework rather than exemptions. For example, reinstatement of habitats on temporarily acquired land is treated as non-significant and does not require legal securing — but this is a calculation treatment, not an exemption from BNG overall. [4]
For a full list of what is currently exempt under the TCPA regime (not NSIPs), see exempt projects guidance.
Common Mistakes Developers Make with BNG — and How to Avoid Them
Several errors are already emerging in early NSIP pre-application work:
- Surveying too late: Baseline habitat surveys need to be completed well before the DCO application is lodged. Starting surveys after pre-application consultation is underway risks programme delay.
- Misdefining the BNG boundary: Including all habitats within the Order limits, rather than only those that are impacted or used to deliver gain, inflates the baseline and complicates the metric calculation. [4]
- Treating temporary land incorrectly: Assuming all temporarily disturbed habitats must be legally secured. Only habitat creation and enhancement counted towards post-development value needs securing. [4]
- Underestimating off-site procurement lead times: High-quality off-site biodiversity units in the right geographic area can take months to procure. Build this into the programme early.
- Ignoring the 30-year obligation in cost planning: Management and monitoring costs over 30 years are material. Developers who omit these from financial models face surprises post-consent.
For a structured approach to planning BNG into a project from the outset, see 8 biodiversity net gain points on planning your project.
Where to Find the Official BNG Guidance Documents
Defra published the ten biodiversity gain statements and accompanying guidance on 4 June 2026. The primary sources are:
- The GOV.UK collection page for BNG and NSIPs [1]
- The Defra environment blog post confirming the statements and guidance [2]
- The Planning Inspectorate's pre-application and examination guidance (updated to reflect BNG requirements)
Legal commentary from BCLP Law [3] and HSF Kramer [4] provides useful practitioner analysis of the statements. LexisNexis has also published a detailed legal guidance note on the NSIP BNG framework. [5]
For a practitioner overview of the secondary legislation underpinning BNG more broadly, see secondary BNG legislation: summary.
Conclusion: What to Do Now Before 2 November 2026
The mandatory BNG NSIPs 2 November 2026 biodiversity gain statements June 2026 update confirms that the NSIP regime is fully defined and the clock is running. For any project targeting a DCO application in late 2026 or 2027, the window to act is narrow.
Immediate actions for ecologists and developers:
- Review the relevant biodiversity gain statement for your NSIP category and cross-reference with Defra's published guidance.
- Commission pre-application baseline habitat surveys now, scheduling fieldwork to capture optimal survey seasons.
- Run an early-stage Biodiversity Metric calculation to identify the likely scale of BNG required and whether off-site units will be needed.
- Integrate BNG boundary definition into DCO Order limits work — coordinate with the legal and planning teams early.
- Build 30-year management and monitoring costs into project financial models.
- Review pre-application consultation materials to ensure BNG is addressed substantively, given its expected prominence in DCO examinations. [3]
- If off-site units are needed, begin procurement conversations with habitat bank providers now.
The biodiversity gain statements published in June 2026 give NSIP promoters the certainty they need to move forward. The projects that will be best placed on 2 November 2026 are those that started their BNG work months before the deadline.
Frequently Asked Questions
Does mandatory BNG apply to NSIPs submitted before 2 November 2026?
No. Mandatory BNG applies only to DCO applications submitted to the Planning Inspectorate on or after 2 November 2026. Projects that have already submitted their application are not captured by the new requirement. [1]
How many biodiversity gain statements were published, and what do they cover?
Ten biodiversity gain statements were laid before Parliament in early June 2026, each covering a specific NSIP category such as energy, transport, water resources, and airports. Together they confirm the calculation, delivery, and reporting framework for all NSIP types. [2]
Does the proposed 0.2 ha small-site exemption apply to NSIPs?
No. The proposed exemption for sites of 0.2 hectares or below arose from a separate consultation that closed on 10 June 2026 and relates solely to Town and Country Planning Act development. It has no bearing on the NSIP BNG regime.
What is the minimum BNG percentage required for NSIPs?
All NSIP applicants must deliver at least 10% biodiversity net gain, consistently applied across all project categories. [3]
Do habitats on temporarily acquired land need to be legally secured?
Reinstatement of existing habitats on temporarily acquired land is treated as non-significant and does not require legal securing. However, any habitat creation or enhancement counted towards post-development biodiversity value must be legally secured. [4]
How long must biodiversity gains be maintained?
Gains must be maintained and monitored for a minimum of 30 years, secured through appropriate legal mechanisms such as conservation covenants or management agreements.
References
[1] Biodiversity Net Gain Nationally Significant Infrastructure Projects – https://www.gov.uk/government/collections/biodiversity-net-gain-nationally-significant-infrastructure-projects
[2] Biodiversity Net Gain For NSIPs: Gain Statements Laid And Guidance Published – https://defraenvironment.blog.gov.uk/2026/06/04/biodiversity-net-gain-for-nsips-gain-statements-laid-and-guidance-published/
[3] Publication Of Biodiversity Gain Statements Confirms BNG Details For NSIPs – https://www.bclplaw.com/en-US/events-insights-news/publication-of-biodiversity-gain-statements-confirms-bng-details-for-nsips.html
[4] BNG For NSIPs: Government Response Confirms Go-Live On 2 November 2026 – https://www.hsfkramer.com/notes/energy-and-infra-consenting/2026-posts/bng-for-nsips-government-response-confirms-go-live-on-2-november-2026
[5] Biodiversity Net Gain For Nationally Significant Infrastructure Projects In England – https://www.lexisnexis.com/en-gb/legal/guidance/biodiversity-net-gain-for-nationally-significant-infrastructure-projects-in-england
