Policy paper

Nationally significant infrastructure projects: biodiversity gain statement for development where no National Policy Statement has effect (accessible version)

Updated 16 June 2026

Applies to England

Presented to Parliament pursuant to paragraph 10(5)(a) of Schedule 2A to the Planning Act 2008

© Crown copyright 2026

ISBN 978-1-5286-6479-0

1. Purpose

1.1. Biodiversity net gain (BNG) is an approach to development that aims to leave the natural environment in a measurably better state than it was in beforehand. Nationally significant infrastructure projects (NSIPs) are large scale developments which deliver essential services and contribute to economic growth. By applying BNG to NSIPs, this much needed infrastructure can be delivered alongside the wider benefits of protecting and restoring nature at scale.

1.2. The Planning Act 2008, as amended by Section 99 and Schedule 15 of the Environment Act 2021, introduces a BNG requirement for NSIPs through amendments to sections 103 to 105 and the insertion of Schedule 2A.^{[footnote 1]} Under this statutory framework, the Secretary of State may not grant an application for development consent unless satisfied that the proposed development meets the biodiversity gain objective as set out in the relevant biodiversity gain statement to which the development relates.

1.3. The purpose of this biodiversity gain statement is to set out the biodiversity gain objective and the process through which biodiversity gains must be calculated, demonstrated, and verified. This statement details how applicants for Development Consent Orders (DCOs) of any NSIPs where no National Policy Statement (NPS) has effect can achieve the biodiversity gain objective. It provides the basis for the BNG aspect of the examination by the Examining Authority and decisions by the Secretary of State on applications for DCOs. Applicants should also have regard to the relevant government guidance on BNG for NSIPs, which supports this statement.

2. Scope of the biodiversity gain statement

2.1. The biodiversity gain objective set out in this statement applies to NSIP applications for DCOs submitted under section 37 and determined under section 104 or 105 of the Planning Act 2008 but only in cases where no NPS has effect, unless it is excluded development.^{[footnote 2]}

2.2. It also applies to applications made following a direction under section 35 of the Planning Act 2008 (where the Secretary of State directs that a project should be treated as development for which development consent is required).

2.3. The biodiversity gain objective only applies to NSIPs, or components of NSIPs, in England. Where NSIP project boundaries include areas outside England, the BNG requirement only applies to the components of the project in England.

2.4. The BNG requirement applies to NSIP projects, or components of projects as far as the mean low-water mark, including the intertidal zone. Projects, or components of projects, in the marine environment beyond the intertidal zone are not included within the scope of the biodiversity gain objective.

3. Biodiversity gain objective

3.1. The biodiversity gain objective requires that the biodiversity value attributable to a development exceeds the pre-development biodiversity value of the on-site habitat by at least 10%. This is also referred to as 10% BNG. The following sections of this biodiversity gain statement detail how the biodiversity gain objective must be calculated, met and evidenced.

3.2. The biodiversity gain objective must be met for DCO applications:

• for development of the description set out in paragraphs 2.1 and 2.2 of this biodiversity gain statement

• made on or after 2 November 2026 until the statement is amended or revoked

4. Mitigation hierarchy

4.1. BNG should be applied alongside the mitigation hierarchy.^{[footnote 3]} Applicants should avoid significant harm to biodiversity resulting from the proposed development in the first instance. Where it is not possible to avoid significant harm to biodiversity, applicants should include appropriate mitigation measures to reduce the impact, and as a last resort, provide compensation for any harm to biodiversity. Applicants must include detail in their outline biodiversity gain plan on how their proposals follow the mitigation hierarchy.

5. Calculating BNG

5.1. Applicants must use the statutory biodiversity metric (referred to in paragraph 4 of Schedule 7A to the Town and Country Planning Act 1990) to calculate the biodiversity value or relative biodiversity value of any habitat or habitat enhancement for the purpose of meeting the biodiversity gain objective. The statutory biodiversity metric should be applied alongside wider ecological consideration and judgement to ensure the proposed project will deliver positive outcomes for nature. The statutory biodiversity metric calculation tool must be used to prove the statutory metric formula has been applied properly. To inform the proper use of the statutory biodiversity metric calculation tool, users must have regard to the full statutory biodiversity metric package (including the statutory biodiversity metric guidance and condition assessments).

5.2. For a development to meet the biodiversity gain objective, the biodiversity value attributable to a development (which may include on-site units, off-site units and statutory biodiversity credits) must exceed the pre-development biodiversity value of the on-site habitat by at least 10%.

6. The pre-development biodiversity value (baseline value)

6.1. The baseline must include the pre-development biodiversity value of habitats within the order limits ^{[footnote 4]} that will be negatively impacted by the development (through temporary or permanent habitat loss or deterioration). It must also include the pre-development biodiversity value of any areas of habitat within the order limits that will be used to contribute towards BNG (where on-site biodiversity gains will be located) through enhancement or creation of new habitat.

6.2. Habitats within the order limits that will remain unimpacted by the development do not need to be included in the baseline, although applicants may choose to voluntarily include them.

6.3. Applicants must provide a BNG boundary plan in their outline biodiversity gain plan. The BNG boundary plan must show the entire order limits with the BNG boundary overlaid, and must differentiate the following categories:

• areas of habitat that will be negatively impacted

• areas of habitat that will be used to contribute towards BNG

• unimpacted habitat included in the BNG boundary and baseline (retained habitat)

• unimpacted habitat within the order limits that are excluded from the BNG boundary and baseline

6.4. For the purpose of this statement and associated guidance, all habitats within the BNG boundary are referred to as ‘on-site’.

6.5. Where there are areas of design uncertainty or limits of deviation, applicants must apply the realistic worst-case extent of habitat loss or deterioration based on the maximum design and construction parameters. It must include all expected areas of habitat loss or deterioration from the development, including permanent and temporary impacts from construction, enabling works, access routes, and associated development. This approach ensures the BNG strategy demonstrates how 10% BNG will be delivered in a realistic worst-case scenario and avoids underestimating habitat losses.

6.6. The baseline and BNG boundary plan must be updated in subsequent updated and phase biodiversity gain plans and metric calculations if the extent or value of habitat loss and deterioration is greater than in the outline biodiversity gain plan.

6.7. The baseline may also be updated in subsequent updated and phase biodiversity gain plans and metric calculations where applicants can demonstrate, through detailed design or construction plans, that habitat impacts will be lower than in the outline biodiversity gain plan. Any changes to the baseline must be clearly documented in updated or phase biodiversity gain plans, including:

• an updated BNG boundary plan showing revised habitat parcels included in the baseline

• a clear description and justification for the changes, supported by evidence of changes to project design, location or construction practices that reduced impacts

Baseline date

6.8. The baseline used in the outline biodiversity gain plan and in the statutory biodiversity metric calculation must be calculated with reference to the date of the outline biodiversity gain plan submission, to ensure it reflects the value of habitat on the date of submission.

6.9. When the biodiversity gain plan or phase plans are updated prior to commencement of development, or a phase of development, the baseline must be calculated with reference to the date of submission of the updated plan.

Surveys

6.10. Survey data must be collected within an appropriate timeframe prior to submission of the outline biodiversity gain plan and updated or phase biodiversity gain plan, taking into account the habitats present and industry best practice guidance on survey data validity, to ensure it reflects the condition of the on-site habitat on the date of submission.

6.11. Older surveys outside the best practice timescales may only be used if the applicant’s ecologist can confirm in their biodiversity gain plan there has been no material change to the on-site habitats since the survey date.

6.12. Surveys from the outline gain plan may be used in updated or phase plans if the applicant’s ecologist can confirm that no material changes to habitats have occurred. Where changes have taken place, updated surveys must be carried out to reflect the current condition - this may apply to part or all of the development site.

6.13. Where it is not possible to access any part of the site and there is insufficient alternative evidence about the biodiversity value of the habitats on the site at the outline biodiversity gain plan stage, the baseline calculation should be taken to be the highest biodiversity value of the on-site habitat which is reasonably supported by the available evidence relating to the site (for example aerial images, photographs, geographic information system (GIS) data layers). For the subsequent updated or phase biodiversity gain plans, additional surveys should be carried out to replace these assumptions where possible, to ensure an accurate reflection of the baseline value before development commences. 

Earlier date

6.14. An earlier baseline date should be discussed with the Examining Authority and subsequently agreed with the Secretary of State in the following circumstances:

• if unauthorised degradation has taken place before the submission of the DCO application

• if activities carried out in connection with an existing planning permission or DCO that has not begun or has not been completed result in a lower biodiversity value of the on-site habitat than it would otherwise have been – for example, if a site is cleared under an existing planning permission, but the development is not built

6.15. The earlier date should be used consistently across all outline, updated or phase biodiversity gain plans and biodiversity metric calculations for the project.

6.16. An earlier baseline date for an updated or phase biodiversity gain plan should also be agreed with the discharging authority in the following circumstances:

• if unauthorised degradation has taken place on-site after submission of the DCO application and before the submission of an updated or phase biodiversity gain plan

• if activities carried out in connection with an existing planning permission or different DCO that has not begun or has not been completed have taken place on-site after submission of the DCO application and before the submission of an updated or phase biodiversity gain plan, and result in a lower biodiversity value than the baseline in the outline biodiversity gain plan

• if habitat clearance permitted through the DCO takes place on-site before the submission of an updated or phase biodiversity gain plan

6.17. The earlier date should be immediately before the degradation activities were carried out, or the closest date prior to the degradation that sufficient data on the biodiversity value of the site is available. If there has been degradation and there is insufficient evidence about the biodiversity value of the on-site habitat immediately before the degradation, the baseline value of the on-site habitat should be taken to be the highest biodiversity value of the habitat which is reasonably supported by any available evidence relating to the site (for example, aerial images, photographs, GIS data layers).

6.18. Applicants are encouraged to engage with the Planning Inspectorate at the pre-application stage, and the relevant discharging authority before the submission of an updated or phase biodiversity gain plan, to discuss the need for an earlier baseline date. If an earlier date is used, applicants must justify the date used in the biodiversity gain plan, and provide supporting evidence.

Development on registered biodiversity gain sites

6.19. If a proposed development will take place on a registered biodiversity gain site, the applicant must use the projected size, type and condition of habitats, as recorded on the register, as the baseline in the metric calculation for that land.

6.20. Where development is proposed on land containing significant on-site biodiversity gains secured through another planning permission or DCO, the applicant must also use the projected size, type and condition of habitats as the baseline in the metric calculation for that land, where this information is available.

7. Delivering BNG

7.1. The biodiversity value attributable to a development can include, in the first instance, either or both of the:

• post-development biodiversity value of the on-site habitat (on-site gains)

• biodiversity value of any registered off-site biodiversity gain allocated to the development (off-site gains)

7.2. As a last resort option, it can include the biodiversity value of any statutory biodiversity credits purchased for the development.

The post-development biodiversity value of the on-site habitat (on-site gains)

7.3. To deliver BNG, developers can create or enhance habitat on-site.

7.4. The on-site post development biodiversity value is the projected value, calculated by the statutory biodiversity metric, of retained, reinstated, enhanced or newly created habitats on-site, provided that they are appropriately maintained and secured (as explained below).

Significant gains

7.5. All habitat creation and enhancement on-site that is counted towards the post-development biodiversity value (except for the purposes of reinstatement, which is defined below), is considered significant.

7.6. Significant on-site gains must be maintained for at least 30 years from the completion of the habitat creation or enhancement works. The maintenance of significant on-site gains must be secured through requirements in the DCO, planning obligations or conservation covenants, and must have a habitat management and monitoring plan that covers this entire period. If the lifespan of the project is longer than 30 years, the habitat should still be generally maintained for this remaining period.

Non-significant gains

7.7. Retained habitats or habitats which have been temporarily impacted and reinstated are considered non-significant. They can be included in metric calculations to contribute to the post-development biodiversity value but do not have to be secured.

7.8. A habitat is considered reinstated if it will be replaced with the same habitat type and condition as was lost.

The biodiversity value of any off-site biodiversity gain allocated to the development (off-site gains)

7.9. For an applicant to meet their BNG requirement, they can also attribute biodiversity value to the development through allocating registered off-site biodiversity gain^{[footnote 5]} (on the biodiversity gain site register) to the development.

7.10. All off-site biodiversity gains will be appropriately secured with a legal agreement to ensure they are created and maintained for at least 30 years, as required by the biodiversity gain sites register. This could be in the form of a conservation covenant or planning obligation.

7.11. The allocation of registered off-site gains must be recorded on the biodiversity gain site register, and the reference number must be added to the updated or phase biodiversity gain plans in line with timings approved in the outline biodiversity gain plan.

Statutory biodiversity credits

7.12. If applicants cannot meet the BNG requirement through on-site and off-site units, they can, as a last resort, purchase statutory biodiversity credits from the UK government. Applicants must provide evidence in their biodiversity gain plan that they were unable to meet the biodiversity gain objective through on-site and off-site options and that statutory biodiversity credits have only been used as a last resort.

Excess gains

7.13. If a development delivers on-site biodiversity gains that exceed the 10% required to meet the biodiversity gain objective, these additional gains can either be:

• secured and attributed to the proposed development as additional on-site gains

• legally secured, registered, and allocated as off-site gains for another development, in accordance with the requirements for biodiversity gain sites

7.14. Applicants must confirm in their outline biodiversity gain plan, and in any updated or phase biodiversity gain plans, if any excess gains are attributed to the development or are available to be allocated to another development. This ensures the Secretary of State can accurately assess the biodiversity outcomes associated with the application.

Interaction with other policies and obligations

7.15. BNG will be delivered alongside existing environmental policies and obligations and does not change or replace these.

7.16. Some habitat creation or enhancement for other purposes (such as green infrastructure, protected sites and species mitigation and compensation, and sustainable drainage) may be able to count towards the biodiversity gain objective in part or in full. Applicants must adhere to the latest guidance on how to count other schemes towards BNG. If an applicant proposes to count other habitat creation or enhancement work towards BNG, they must include it in the metric calculation and the biodiversity gain plan.

8. Irreplaceable habitat

8.1. Irreplaceable habitats are those which would be technically very difficult (or take a very significant time) to restore, recreate or replace once destroyed. The biodiversity gain objective does not change the existing protections and compensation requirements for irreplaceable habitat. Where a proposed development will result in the loss or deterioration of any irreplaceable habitats, applicants and decision makers should refer to relevant planning policy and guidance on irreplaceable habitats.^{[footnote 6]}

How BNG applies to development on irreplaceable habitat

8.2. Irreplaceable habitat for the purpose of BNG is defined in Regulation 2 of The Biodiversity Gain Requirements (Irreplaceable Habitat) Regulations 2024 or any future update.

8.3. The biodiversity gain objective is applied differently where there is irreplaceable habitat on-site (within the BNG boundary). This is because the loss or deterioration of irreplaceable habitat cannot be adequately captured by the biodiversity metric alone.

8.4. All irreplaceable habitats must be recorded in the irreplaceable habitat sheet of the biodiversity metric tool as detailed in the user guide. However, the biodiversity value of the irreplaceable habitat will not be included in the baseline, and the 10% biodiversity objective will not apply, unless there is a proposed enhancement to the irreplaceable habitat.

8.5. Where there are losses or deterioration to irreplaceable habitat on-site, there must be a suitable bespoke compensation strategy. The compensation strategy must be relative to the pre-development habitat type and cannot involve the purchase of statutory biodiversity credits. Compensation agreed for the loss or deterioration on irreplaceable habitat cannot count towards the 10% biodiversity gain objective.

8.6. Bespoke compensation is not necessary if evidence confirms there will be no losses or deterioration to the irreplaceable habitats.

8.7. Where there are proposed enhancements to irreplaceable habitat on-site, the biodiversity value of the irreplaceable habitat is included in the calculation of baseline, and the 10% biodiversity gain objective applies. As there are no negative effects on the habitat, a bespoke compensation package is not necessary. The value of the proposed enhancement to the irreplaceable habitat can contribute towards the 10% biodiversity gain objective. Enhancement works must be ecologically appropriate and not have any adverse impacts on irreplaceable habitat.

8.8. When development sites contain irreplaceable and non-irreplaceable habitat, the biodiversity gain objective must still be met for any non-irreplaceable habitat present on-site.

9. Evidence for submission

Pre-application

9.1. During pre-application, applicants are encouraged to share the indicative BNG requirement for the project (calculated using the statutory biodiversity metric) and their proposed approach to deliver the required gains with the Planning Inspectorate and other relevant stakeholders, to help inform the development of the outline biodiversity gain plan.

Evidence for submission – application stage

9.2. Applicants must submit an outline biodiversity gain plan to the Planning Inspectorate as part of their DCO application. The purpose of the outline biodiversity gain plan is to set out a strategy for how the proposed development will deliver the statutory biodiversity gain objective of at least 10%.

9.3. The outline biodiversity gain plan must include the following matters:

1. Name and address of the applicant, and (if different) the person completing the plan.

2. A brief statement outlining the role and input of qualified ecological professionals in preparing the biodiversity gain plan, including the biodiversity metric calculation and habitat management and monitoring plan.

3. A description of the development to which the plan relates.

4. Statement confirming that the baseline reflects the value of the on-site habitat on the date of gain plan submission, or an earlier date. If using an earlier date, justification and evidence for proposing that date.

5. A BNG boundary plan drawn to an identified scale, showing the direction of north, and identifying the different habitat impact categories (lost or deteriorated habitat, areas of habitat used to contribute towards BNG, unimpacted habitat included in the baseline, and unimpacted habitat excluded from the baseline).

6. The completed biodiversity metric calculation tool, stating the publication date of the tool, and showing the calculation of the baseline and the post-development biodiversity value. If the applicant proposes to submit biodiversity gain plans for approval on a phased approach, this must also include the post-development biodiversity value of the on-site habitat for each phase of development.

7. Supporting detail to describe and justify the proposed use of biodiversity metric multipliers and rules, where relevant.

8. Proposed arrangements for maintenance and monitoring of significant on-site gains. If these significant on-site gains will be secured through a DCO requirement, a draft habitat management and monitoring plan must be provided.

9. A description and a plan showing the location of any irreplaceable habitat within the BNG boundary on the baseline date, and where necessary, a compensation strategy for any impacts of the development resulting in loss or deterioration of the irreplaceable habitat.^{[footnote 7]} The compensation strategy may need to be updated after submission to reflect changes in anticipated impacts to the irreplaceable habitat, feedback from consultees, or new ecological survey data.

10. Information about the steps taken or to be taken to avoid and minimise the adverse effect of the development on the biodiversity of the on-site habitat and any other habitat, including irreplaceable habitat (how the mitigation hierarchy is being followed).

11. Strategy to meet the biodiversity gain objective, including the proposed use of any on-site gains, off-site gains, and statutory biodiversity credits, and a schedule for securing these gains, which must ensure all final gains are secured before the operation of the project at the latest.

12. Description of any remaining uncertainty on the detailed design of the proposed development, and how any changes to the BNG requirement will be addressed.

13. Where applicable, confirmation on whether excess on-site biodiversity gains will be secured and attributed to the proposed development or will be allocated to another development. Provide detail to identify the excess gains including the location within the BNG boundary.

9.4. Applicants may also submit other relevant information in their outline biodiversity gain plan to help demonstrate to the Secretary of State that the biodiversity gain objective for the development is met.

9.5. Applicants must propose requirements in the draft DCO to secure the biodiversity gain objective.

9.6. Requirements must secure the following:

1. 1. Either an updated biodiversity gain plan must be submitted and approved prior to commencement of development, or a phase biodiversity gain plan must be submitted and approved prior to commencement of each phase of development. These updated plans must include:

   1. a) An updated metric calculation.

   2. b) Evidence of any biodiversity units that have already been secured. This evidence can include:

      1. i. significant on-site gains with a habitat management and monitoring plan secured either through a requirement in the DCO, conservation covenant or s106 agreement.

      2. ii. registered off-site biodiversity gain allocated to the development

      3. iii. statutory biodiversity credits purchased for the development

   3. c) Detail and justification for any changes from the approved outline gain plan.

   4. d) Strategy to secure the remaining biodiversity units needed to meet the biodiversity gain objective, including the proposed use of any additional registered off-site biodiversity gains or statutory biodiversity credits, and planned times to secure these units.

   5. e) Any other matters identified in the outline biodiversity gain plan for subsequent approval.

2. 2. Any final shortfall in biodiversity units to meet the biodiversity gain objective must be calculated and any outstanding units must be secured before the operation of the project at the latest.

3. 3. The biodiversity gain objective must be implemented as set out in the approved outline biodiversity gain plan and any subsequent approved updated biodiversity gain plans or phase biodiversity gain plans.

4. 4. If applicants propose to secure any significant on-site biodiversity gains through requirements in the DCO, they must include these provisions in the draft DCO. This must secure:

   1. a) The submission of a habitat management and monitoring plan for approval as part of the updated biodiversity gain plan prior to commencement of development.

   2. b) That habitats are managed and maintained for at least 30 years from the habitat creation or enhancement works and monitoring reports are submitted, in line with the approved habitat management and monitoring plan.

   3. c) The habitat management and monitoring plan is updated and reapproved if there are changes to the significant on-site gains allocated to the development as part of subsequent updates to the biodiversity gain plan or metric calculations.

9.7. The relevant discharging authority for these BNG requirements must be specified in the DCO requirements. This will normally be the relevant planning authority, which could be the host local planning authority or a lead local planning authority where there are multiple hosts. Alternatively, the Secretary of State may be the discharging authority in consultation with relevant planning authorities. If the applicant proposes to submit biodiversity gain plans for approval on a phased approach, this should be discussed with the Planning Inspectorate and the relevant discharging authority at the pre-application stage.

9.8. Applicants should secure as many units as can reasonably be secured prior to commencement of development, only leaving any final shortfall where there is substantial uncertainty in the exact scale or type of habitats that will be impacted by the development.

9.9. For further information, applicants should refer to guidance on biodiversity gain plans and securing BNG. To avoid duplication in reporting, applicants can cross-refer to relevant information submitted in other documents and previous biodiversity gain plans where applicable.

10. Decision making

10.1. In accordance with sections 104 and 105 of the Planning Act 2008, the Secretary of State will not grant an application for development consent unless satisfied that the proposed development meets the biodiversity gain objective contained in this biodiversity gain statement. The Secretary of State can consider the biodiversity gain objective as met if there are requirements in the DCO securing it will be met.

1. Section 99 of and Schedule 15 to the Environment Act 2021 introduced the requirement for biodiversity net gain in relation to NSIPs by way of the amendment to Sections 103 to 105 and the insertion of the new Schedule 2A to the Planning Act 2008. ↩

2. Schedule 2A, paragraph 1(2) of the Planning Act 2008 includes provisions for development to be excluded from the biodiversity gain objective through regulations made by the relevant Secretary of State. No regulations have been made at the time of writing. ↩

3. The principle that environmental harm resulting from a development should first be avoided, adequately mitigated, or, as a last resort, compensated for. The mitigation hierarchy is set out in the National Planning Policy Framework (NPPF). The NPPF may be considered as a matter that is both important and relevant to the Secretary of State’s decision. ↩

4. The order limits are the geographic limits of the powers the applicant is seeking through the DCO. ↩

5. Registered off-site biodiversity gain as defined in paragraph 10 of Schedule 7A to the Town and Country Planning Act 1990. ↩

6. The NPPF may be considered as a matter that is both important and relevant to the Secretary of State’s decision. ↩

7. This compensation strategy may also be required to meet wider planning policy on irreplaceable habitat as set out in the NPPF. The NPPF may be considered as a matter that is both important and relevant to the Secretary of State’s decision. The same compensation strategy can be used for both purposes. ↩