Biodiversity Net Gain for NSIPs: What developers need to know
Biodiversity Net Gain (“BNG”) is now mandatory for Nationally Significant Infrastructure Projects (“NSIPs”) in England, with the new requirements applying to Development Consent Order (“DCO”) applications made on or after 2 November 2026. We summarise the key points developers need to consider under the new regime. For more detail on the wider BNG framework, please also see our previous notes from October 2023 and February 2024.
Do NSIPs need to comply with BNG?
Yes. From 2 November 2026, BNG is a mandatory requirement for NSIPs in England. Any NSIP developers applying for Development Consent Order (“DCO”) on or after this date will need to deliver at least 10% net gain in biodiversity. These obligations will be contained within Schedule 15 to the Environment Act 2021. The BNG regime will not apply to infrastructure consented through other routes; the example given by the Government is Hybrid Bills.
How will the regime apply to cross-border NSIPs?
The BNG regime for NSIPs will only apply to land in England. It is very possible that some NSIPs may cross the border from England into Wales or Scotland. BNG calculations for the project will only need to include relevant habitat within England falling within the DCO boundary. Equally any enhancements or habitat creation that will be delivered as part of the required BNG must be delivered in England. BNG can also be delivered on land outside England, but this will be on a purely voluntary basis and must be calculated separately from the statutory requirements.
Will NSIPs need to prepare a biodiversity gain statement?
Yes, DEFRA has published biodiversity gain statements for NSIPs which set out how BNG requirements should be calculated, delivered and reported. The biodiversity gain statement applicable to the relevant NSIP project must be complied with. Any applicable BNG requirements will sit alongside existing environmental and statutory obligations; these are not replaced or amended by the introduction of the BNG regime for NSIPs.
What is taken into account in the calculation of the BNG baseline for NSIP developments?
Statutory metric tools and guidance are available to calculate the baseline value of onsite habitats for NSIP projects. For NSIP purposes, the baseline calculation must include the pre‑development biodiversity value of any habitat within the Order limits that will be (1) negatively impacted by the development; and (2) used to contribute towards the development’s BNG.
The area from which the baseline is calculated is the BNG boundary. This will not necessarily be the same as the full extent of the DCO Order limits which will be the geographic limits of the powers the applicant is seeking. As the site layout develops or is amended during the design process, the BNG boundary may need to change to reflect those updates. The baseline calculation would therefore also need to be updated.
Is it possible to exclude any habitats from the baseline calculation?
If it can be confirmed that there are no expected impacts to any onsite habitats from the proposed NSIP development, those unimpacted habitats can be excluded from the baseline calculation.
The Government guidance gives the example of infrastructure located above or below ground level. The habitat beneath or above it respectively may fall within the Order limits but remain unaffected by the proposed development.
It is possible to choose to include unimpacted habitats in the baseline. Where this is done, those habitats will also be subject to the 10% BNG objective.
Can NSIP developments benefit from onsite delivery, offsite gains and statutory credits?
NSIPs can deliver the 10% BNG increase via all three options of onsite, offsite and statutory credits. For NSIP projects, both the onsite gains and offsite gains can be considered at the same time. For NSIP purposes, onsite means any areas within the BNG boundary.
Onsite and offsite options can therefore be considered alongside each other as the first means of meeting the 10% gain objective. Statutory credits remain a last resort, after onsite and offsite opportunities have been exhausted without meeting the full 10% gain requirement. If statutory credits are required, it must be demonstrated why the BNG requirement cannot be met through a combination of onsite and offsite options.
How are onsite gains considered for NSIPs?
Onsite habitat creation or enhancement is considered to be significant in all cases. Significant onsite gains must be maintained and secured for 30 years.
Any habitat which is retained or will be reinstated is considered non-significant. That habitat does not need to be secured for 30 years and can count towards the BNG uplift. It is a requirement that reinstated habitats must be returned to their original positions.
How are offsite gains treated for NSIPs?
In the context of NSIPs, offsite means any habitat outside of the BNG boundary.
Offsite gains can be delivered either by creating units on other land owned by the NSIP developer or by purchasing units from landowners in the BNG market. Given that NSIPs may require large numbers of offsite units across a range of habitat types, sourcing the necessary units may be more challenging and suitable units may not always be readily available. Early engagement with the offsite market is therefore likely to be helpful in securing the units needed.
What needs to be included in the DCO application?
The DCO application needs to include an outline biodiversity net gain plan and draft DCO requirements relevant to BNG. The DCO application will only be consented by the Secretary of State if they are satisfied that the 10% BNG objective can be met in line with the applicable biodiversity gain statement for the relevant type of project.
A schedule for securing any required gain must be included in the outline gain plan, setting out reasonable timeframes for securing those gains. This is not required if all of the relevant gain will have been secured by the time the Development Consent Order is granted. The Government gives the example of gains secured through section 106 agreements or conservation covenants.
Once consent is granted, the gains will need to be secured in line with the relevant schedule. Before development can commence pursuant to the DCO once granted, as many offsite units as reasonably possible will need to have been secured in line with the schedule agreed in the approved outline gain plan.
Please get in touch with our planning team for advice on how the BNG requirements may apply to a particular project or site.
Information correct as of November 2026. This note is a summary; please refer to legislation and guidance for full details.
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