Last updated: August 16, 2026
Quick Answer: From 2 November 2026, any Nationally Significant Infrastructure Project (NSIP) in England that submits a Development Consent Order (DCO) application on or after that date must deliver at least 10% biodiversity net gain compared to the pre-development baseline. The requirement is mandatory, applies across onshore NSIPs down to the mean low-water mark, and is enforced through the DCO process rather than the Town and Country Planning Act regime. Developers who have not yet begun baseline surveys or secured off-site units are already behind schedule.
Key Takeaways
- 2 November 2026 is the confirmed commencement date for mandatory BNG NSIP November 2026 nationally significant infrastructure projects biodiversity net gain obligations, set by secondary legislation laid before Parliament [2].
- DCO applications submitted before 2 November 2026 are outside the mandatory duty; there is no retrospective application [2][7].
- The 10% net gain minimum is calculated using the statutory biodiversity metric, comparing post-development habitat value to the pre-development baseline within the order limits [6][10].
- BNG for NSIPs applies onshore only, down to the mean low-water mark; marine works beyond that boundary are excluded [4][7].
- The delivery hierarchy is: onsite creation or enhancement first, then off-site purchased units, then statutory biodiversity credits as a last resort [8].
- Biodiversity enhancements must be secured and maintained for a minimum of 30 years [8][10].
- Off-site units can be sourced from any relevant local planning authority without a spatial risk multiplier penalty, which is a key difference from the TCPA regime [8].
- A biodiversity gain plan and completed statutory metric calculation must be submitted with the DCO application, not post-consent [8][15].
- Procurement lead times for off-site units can exceed 12 months; developers targeting a 2027 DCO submission should be securing units now [7].
- Defra has published sector-specific biodiversity gain statements, including one for data centres, as model text aligned with relevant National Policy Statements [1][2][10].
What Is Biodiversity Net Gain and Why Does It Matter for Infrastructure?
Biodiversity net gain (BNG) is a legally mandated approach that requires development to leave habitats measurably better than they were before construction began. For infrastructure developers, it means that every DCO application must demonstrate a quantified improvement in biodiversity value, not simply avoid harm.
The statutory framework originates in the Environment Act 2021, which introduced mandatory BNG for Town and Country Planning Act (TCPA) consents in England. The extension to NSIPs via the BNG NSIP November 2026 nationally significant infrastructure projects biodiversity net gain regime closes the final major gap in that framework. Without this extension, some of England's largest and most ecologically significant development projects would have remained outside the mandatory net gain duty.
For a broader overview of why this matters to the UK planning system, see biodiversity net gain explained.
Which Infrastructure Projects Need Biodiversity Net Gain?
NSIPs are projects that meet specific thresholds under the Planning Act 2008, requiring a DCO from the Secretary of State rather than local planning permission. They include:
- Energy: onshore wind farms above 50 MW, offshore wind above 100 MW (onshore elements only), gas and oil pipelines, electricity transmission lines
- Transport: nationally significant road and rail schemes, including those promoted by National Highways and Network Rail
- Water: reservoirs with a capacity above 10 million cubic metres, water transfer projects
- Waste water and hazardous waste facilities above defined thresholds
- Data centres (newly designated as a category following 2024 legislation) [10]
- Ports and harbours above specified throughput thresholds (onshore and intertidal elements only) [4][7]
The BNG duty applies only to the onshore portion of these projects, down to the mean low-water mark. Works in the marine environment beyond that point fall under separate marine licensing and are excluded from the NSIP BNG regime [4][7].
Common mistake: Assuming that because a project is primarily offshore or in a tidal zone, no BNG applies. If any part of the order limits sits onshore or in the intertidal zone, the full 10% duty is triggered for those habitats.
What Changed in BNG NSIP Requirements in November 2026?
The 2 November 2026 date is the formal commencement of mandatory BNG for NSIPs, confirmed through secondary legislation and biodiversity gain statements laid before Parliament, with accompanying guidance published by Defra in May, June 2026 [1][2]. This supersedes earlier industry expectations of a May 2026 start date referenced in the Environmental Improvement Plan 2025 [2][4].
Key changes from the pre-November 2026 position:
- BNG moves from voluntary best practice for NSIPs to a statutory requirement enforceable through DCO conditions.
- A biodiversity gain plan and statutory metric calculation must accompany every qualifying DCO application from this date [8].
- Sector-specific biodiversity gain statements now provide model text aligned with National Policy Statements, giving applicants clearer drafting guidance [1][10].
- The Secretary of State retains a power to adjust the 10% minimum in future, but no change is signalled at this stage [5].
How Does BNG Apply to Nationally Significant Infrastructure Projects?
The core obligation is that the biodiversity value attributable to the development must exceed the pre-development biodiversity value of on-site habitat within the order limits by at least 10% [6][10]. This is measured using the statutory biodiversity metric.
Key procedural differences from TCPA BNG:
| Feature | TCPA BNG | NSIP BNG (from 2 Nov 2026) |
|---|---|---|
| Consent route | Local planning authority | Secretary of State via DCO |
| Biodiversity gain plan timing | Post-consent condition | Submitted with DCO application |
| Off-site spatial risk multiplier | Applies by LPA area | No penalty across LPA boundaries [8] |
| Minimum maintenance period | 30 years | 30 years [8][10] |
| Statutory credits | Last resort only | Last resort only [8] |
The requirement to submit the biodiversity gain plan with the DCO application is the most significant procedural shift. Under the TCPA regime, the gain plan is typically approved post-consent as a planning condition. For NSIPs, it must be ready at the point of submission, which substantially increases the preparation burden [8].
How Do You Calculate Biodiversity Net Gain for Large Projects?
The statutory biodiversity metric is the required calculation tool. It assigns a unit value to each habitat type based on area, condition, distinctiveness, and strategic significance. The post-development value (after habitat creation and enhancement) must exceed the pre-development value by at least 10%.
For large NSIP footprints, the calculation covers all habitats within the order limits unless an alternative approach is agreed [6][8]. This creates a specific challenge: order limits for major infrastructure schemes often extend well beyond the actual construction area, potentially capturing habitats that will not be directly disturbed.
Practical steps for the metric calculation:
- Commission a Phase 1 habitat survey and extended Phase 2 surveys where required, timed to capture the best seasonal data.
- Map all habitats within the order limits to the metric's habitat classification system.
- Assess habitat condition using the metric's condition assessment criteria.
- Model the post-development scenario, including onsite mitigation and enhancement.
- Identify any shortfall and quantify the off-site units or statutory credits needed.
- Document all assumptions, particularly for temporary construction areas and phased delivery.
For a detailed breakdown of what a BNG assessment involves, see what is in a biodiversity net gain assessment.
Can You Offset Biodiversity Net Gain Off-Site, or Does It Have to Be On-Site?
Off-site delivery is permitted and, for many large NSIPs, will be necessary. The delivery hierarchy is: onsite first, off-site second, statutory credits only as a last resort [8][12].
A significant advantage for NSIP applicants over TCPA developers is that off-site BNG units can be sourced from any relevant local planning authority across the project's footprint without incurring the spatial risk multiplier that applies under the TCPA regime [8]. This matters for linear infrastructure such as roads, railways, and pipelines that cross multiple LPA boundaries.
Off-site units must be registered on the national biodiversity gain site register. Procurement lead times are a real constraint: identifying suitable land, negotiating agreements, completing habitat surveys, and registering units can take 12 months or more [7]. Developers targeting a DCO submission in 2027 should be in active procurement now.
For a comparison of on-site and off-site delivery options, see biodiversity net gain off-site or on-site delivery.
Who Is Exempt from BNG Requirements for Infrastructure?
Not all development within an NSIP order limit will be subject to the BNG duty. Certain exemptions mirror those in the TCPA regime and include:
- De minimis developments affecting less than 25 square metres of habitat or 5 metres of linear habitat [2]
- Householder applications (not relevant to NSIPs in practice)
- Biodiversity gain sites themselves, where the land is already registered as providing BNG units
- Works in the marine environment beyond the mean low-water mark [4][7]
Post-consent changes to DCOs where the original application pre-dates 2 November 2026 will not trigger the mandatory duty, even if the variation is submitted after that date [2][7]. This transitional protection is firm and provides certainty for schemes already in the pipeline.
For a full list of project types that may be exempt, see exempt projects.
What Are the Penalties for Not Meeting BNG Requirements?
Failure to submit a compliant biodiversity gain plan with a DCO application will result in the application being treated as incomplete and not accepted for examination by the Planning Inspectorate (PINS). There is no discretion to waive the requirement once it is in force [2][8].
Post-consent, failure to secure and maintain biodiversity units in accordance with DCO requirements can constitute a breach of the consent, potentially triggering enforcement action by the relevant authority. The 30-year maintenance obligation is legally binding and secured through DCO requirements, planning obligations, or conservation covenants [8][10].
Edge case: Where a project is phased, biodiversity units must be secured before commencement of each phase, not just at the outset of the overall project. Developers should build phase-specific BNG milestones into their programme from the outset [8].
How Much Does Biodiversity Net Gain Cost for Infrastructure Projects?
Costs vary significantly depending on the project's habitat baseline, the extent of onsite enhancement possible, and the market price of off-site units. There is no single published benchmark for NSIP-scale projects.
The main cost components are:
- Ecological survey and metric calculation: For large NSIP footprints, this can run to tens of thousands of pounds given the survey effort required.
- Onsite habitat creation and enhancement: Costs depend on the habitat type; woodland creation is generally less expensive per unit than wetland or species-rich grassland.
- Off-site biodiversity units: Market prices vary by habitat type, location, and condition. Statutory biodiversity credits (the last-resort option) are priced by Defra and are generally more expensive than private market units to incentivise genuine habitat creation. For current pricing, see cost of biodiversity units and statutory credits.
- 30-year monitoring and management: Often overlooked in early cost estimates but a material long-term liability.
What Habitats Count Most Toward Biodiversity Net Gain?
The statutory metric assigns higher unit values to habitats with greater distinctiveness and ecological significance. High-distinctiveness habitats generate more units per hectare, making them more efficient for meeting the 10% target.
High-value habitat types for BNG purposes include:
- Ancient woodland and veteran trees
- Species-rich grassland (including lowland meadow and upland hay meadow)
- Lowland raised bog and blanket bog
- Fen, marsh, and swamp habitats
- Coastal and floodplain grazing marsh
- Intertidal habitats (relevant for coastal NSIPs)
Conversely, improved grassland, arable land, and urban/suburban habitats carry lower unit values. NSIP projects with large areas of low-distinctiveness habitat in their baseline may find it relatively straightforward to achieve 10% gain through targeted enhancement, while those impacting high-distinctiveness habitats face a more demanding calculation.
What Are Common Mistakes Developers Make with BNG Compliance?
1. Starting surveys too late. Habitat condition assessments must be carried out at the optimal time of year for the habitats present. Missing the survey window by even a few months can delay a DCO application significantly.
2. Underestimating the order limits issue. Including large areas of undisturbed high-quality habitat within order limits can inflate the baseline, making the 10% target harder to achieve. Early engagement with PINS on the scope of the BNG boundary is advisable [6][8].
3. Assuming off-site units will be available on demand. The market for high-quality off-site units in the locations most relevant to large NSIP projects is not unlimited. Early procurement is essential [7].
4. Treating BNG as a standalone exercise. The biodiversity gain plan must be consistent with the Environmental Impact Assessment, Habitats Regulations Assessment, and any species mitigation strategies. Inconsistencies between these documents are a common examination issue [6].
5. Overlooking the 30-year liability. Many developers focus on achieving the 10% figure at the point of consent without adequately planning for long-term monitoring, management funding, and liability transfer.
For more on avoiding these pitfalls, see achieving biodiversity net gain without the risk.
What's the Difference Between BNG and Environmental Impact Assessment?
BNG and Environmental Impact Assessment (EIA) are complementary but distinct obligations. EIA assesses the likely significant effects of a project on the environment, including ecology, and requires mitigation of harm. BNG goes further: it requires a net positive outcome for biodiversity, not just harm mitigation.
A project can satisfy EIA requirements by demonstrating that ecological impacts are mitigated to an acceptable level, yet still fail to meet the BNG 10% target if the residual biodiversity value after mitigation does not exceed the baseline by 10%. The two assessments must be aligned, but neither substitutes for the other [6][8].
Practical Steps Developers Should Take Now (August 2026) to Prepare
With fewer than 90 days until the 2 November 2026 commencement, developers with DCO submissions planned for 2027 or 2028 should be taking the following steps immediately:
- Commission baseline habitat surveys if not already under way. Autumn 2026 surveys are still achievable for many habitat types.
- Run a preliminary statutory metric calculation to identify the likely scale of the BNG shortfall and whether onsite enhancement alone can meet the 10% target.
- Engage a specialist ecologist with NSIP experience to review the order limits and advise on the BNG boundary.
- Begin off-site unit procurement by identifying potential habitat bank sites or approaching landowners. Allow at least 12 months for the full process [7].
- Review Defra's sector-specific biodiversity gain statements relevant to the project type, available via the GOV.UK collection [2][10].
- Align the BNG strategy with the EIA and HRA to avoid inconsistencies that could be raised at examination.
- Engage PINS early through the pre-application process to discuss the proposed BNG approach, particularly if there are complex order limits or phasing arrangements [2].
For a structured planning checklist, see 8 biodiversity net gain points on planning your project.
Conclusion
The BNG NSIP November 2026 nationally significant infrastructure projects biodiversity net gain regime represents the most significant change to the NSIP consenting process since the Planning Act 2008 framework was established. From 2 November 2026, the 10% biodiversity net gain target is a hard legal requirement, not a material consideration to be weighed against other factors.
Actionable next steps for August 2026:
- Confirm whether your project's DCO submission date falls before or after 2 November 2026 and plan accordingly.
- Instruct ecological consultants to begin or accelerate baseline surveys within the order limits.
- Initiate off-site unit procurement without delay, given lead times of 12 months or more.
- Review Defra's published biodiversity gain statements and align your biodiversity gain plan with the relevant sector guidance.
- Engage PINS through the pre-application service to agree the scope of the BNG assessment early.
Developers who treat BNG as an afterthought will face examination delays and potential refusal. Those who integrate it into project design from the outset will find it manageable and, in many cases, an opportunity to deliver landscape-scale habitat improvements that strengthen the overall consenting case.
Frequently Asked Questions
Q: Does the BNG NSIP requirement apply to DCO applications submitted before 2 November 2026?
No. The mandatory duty applies only to DCO applications submitted on or after 2 November 2026. Projects already in the examination or decision pipeline are not affected, and post-consent changes to pre-November 2026 DCOs will not trigger the duty [2][7].
Q: Can statutory biodiversity credits be used to meet the full 10% requirement?
No. Statutory credits are a last resort, available only where onsite and off-site options cannot deliver the required gain. They cannot be used as a primary delivery mechanism [8].
Q: Does BNG apply to the marine elements of an offshore wind farm?
No. The BNG duty applies only to onshore elements, down to the mean low-water mark. Works in the marine environment beyond that boundary are excluded [4][7].
Q: Who approves the biodiversity gain plan for an NSIP?
The Secretary of State, through the DCO process administered by the Planning Inspectorate (PINS), is the consenting authority. The biodiversity gain plan must be submitted with the DCO application and will be examined as part of the overall application [2][8].
Q: How long must biodiversity enhancements be maintained?
A minimum of 30 years, secured through DCO requirements, planning obligations, or conservation covenants [8][10].
Q: Is there a spatial restriction on where off-site BNG units must be located for NSIPs?
No. Unlike the TCPA regime, off-site units for NSIPs can be sourced from any relevant local planning authority without incurring a spatial risk multiplier penalty. This is particularly useful for linear infrastructure crossing multiple LPA boundaries [8].
Q: What happens if a project cannot achieve 10% BNG through any means?
The application would not satisfy the statutory requirement and would be at risk of refusal. In practice, the combination of onsite enhancement, off-site units, and statutory credits means genuine inability to achieve 10% is unlikely for most projects, though it may be costly [8][12].
References
[1] 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/
[2] Biodiversity Net Gain Nationally Significant Infrastructure Projects – https://www.gov.uk/government/collections/biodiversity-net-gain-nationally-significant-infrastructure-projects
[3] Biodiversity Net Gain For Nationally Significant Infrastructure Projects – https://www.gov.uk/government/consultations/biodiversity-net-gain-for-nationally-significant-infrastructure-projects
[4] Biodiversity Net Gain Requirements Extended Nov 2026 – https://www.pinsentmasons.com/out-law/news/biodiversity-net-gain-requirements-extended-nov-2026
[5] Consultation On BNG For NSIPs May 2025 – https://consult.defra.gov.uk/biodiversity-net-gain/biodiversity-net-gain-for-nationally-significant-i/supporting_documents/OFFSEN%20FINAL%20Consultation%20on%20BNG%20for%20NSIPs%20%20May%202025.pdf
[6] BNG NSIPs Defra Response Rollout – https://www.burges-salmon.com/our-thinking/bng-nsips-defra-response-rollout/
[7] Biodiversity Net Gain For NSIPs What Developers And Landowners Need To Know Ahead Of November 2026 – https://www.footanstey.com/our-insights/articles-news/biodiversity-net-gain-for-nsips-what-developers-and-landowners-need-to-know-ahead-of-november-2026/
[8] BNG For NSIPs Government Provides More Detail – https://www.bclplaw.com/en-US/events-insights-news/bng-for-nsips-government-provides-more-detail.html
[10] Nationally Significant Infrastructure Projects Biodiversity Gain Statement For Data Centres – https://www.gov.uk/government/publications/nsips-biodiversity-gain-statement-for-data-centres/nationally-significant-infrastructure-projects-biodiversity-gain-statement-for-data-centres-accessible-version
