GuideBiodiversity Net Gain

Can habitat enhancements be provided in the blueline (wider ownership) boundary for biodiversity net gain?

Yes. However, any habitats provided in the blueline boundary are deemed to be provided offsite and must be entered into the offsite tabs in the biodiversity metric.

Any offsite habitat enhancements, including any proposed in a blueline (ownership) boundary (even if this is adjacent to the redline boundary), must be legally secured for 30-years with a planning obligation (Section 106 agreement), supported by a Habitat Management and Monitoring Pan (HMMP), and registered on the Natural England Gain Site Register before the biodiversity gain condition can be discharged.

Therefore, increasing the redline boundary to accommodate any biodiversity enhancements may be the most cost-effective method to achieve BNG. E.g., any habitat creation/enhancement within the redline boundary would be considered onsite and potentially possible to secure this with a planning condition and avoids the requirement to be registered with Natural England.

My development includes a private garden – what do I need to consider?

Within the Statutory Biodiversity Metric/Small Sites User Guides, private garden is defined as, ‘A garden within the curtilage of a privately owned or tenanted dwelling house.’  

At post-development, biodiversity net gains within a private garden cannot be legally secured; therefore, the only habitats that can be created are:

• ‘urban – vegetated garden’ or
• ‘urban – unvegetated garden’ or
• 'urban - other green roof'

Other key points:

• You should not record enhancement of any habitat within private gardens
• Habitats which are recorded in the baseline and remain within a private garden may be recorded as retained

Which habitats do I need to record within the Biodiversity Metric?

You must record ALL habitats that are within the red line boundary of the planning application site. This includes linear habitats (such as hedgerows, fences, etc), watercourses, and built structures/hardstanding that are either within or on the boundary of the site. In addition, you must record any habitat that is being retained.

For clarity, and in accordance with .GOV guidance, the red line boundary should include all land necessary for the development, including access to the highway and any visibility splay(s). All land within the red line boundary is considered as on-site habitat for BNG in accordance with the BNG user guide and must be recorded. This is a statutory requirement and detailed within the BNG Planning Practice Guidance.

What is meant by a ‘Competent Person’ in relation to completing the Statutory Biodiversity Metric and the Small Sites Metric?

The Statutory Biodiversity Metric and the Small Sites Metric are both underpinned by nine principles. The first principle is ‘The metric assessment should be completed by a competent person’. Competency is aligned with the British Standard Process for designing and implementing biodiversity net gain (BS 8683:2021)

Statutory Biodiversity Metric

The Statutory Biodiversity Metric User Guide describes a ‘competent person’ as someone who ‘has the knowledge and skills to perform specified tasks to complete and review biodiversity metric calculations. You obtain this through training, qualifications, experience, or a combination of them.’

In general terms this would be expected to be a professional ecologist with appropriate training and experience. The ecologist might require support and input from other professionals including landscape designers in completing the assessment

In addition to the above, the user guide also states, ‘You should be a qualified assessor to undertake a river condition assessment.’

Small Sites Metric (SSM)

The Small Sites Metric User Guide describes a ‘competent person’ as someone who:

‘has the knowledge and skills to perform specified tasks to complete and review SSM calculations. You obtain this through training, qualifications, experience, or a combination of them. Users of the SSM should be competent in identifying: habitats present on site (pre-development) and management requirements for habitats to be created or enhanced within the landscape design (post-development).'

This might be a professional ecologist but might also be other natural environment professionals including landscape and tree specialists provided that they can identify the habitats present on the site and make appropriate recommendations and decisions relating to habitat creation and management.

Biodiversity Gain Plan - Helpful Tips

• It is recommended that the Biodiversity gain plan - GOV.UK template is used to bring the information together.
• If a bespoke gain plan is submitted, it should be explicit in how all matters are addressed to discharge the general biodiversity condition. For example, it should clearly reference report title/paragraph/page number(s), Figure/Table references, workbook sheet/cell reference(s) etc. Plans with vague details, e.g., stating ‘it’s within the EcIA report’ will be subject to delays, could result in non-determination, and/or returned to ensure the information is clearly accessible.
• It is recommended that any planning consultation responses are reviewed to ensure that the onsite biodiversity value or ‘baseline’ value is in accordance with any comments, such as required amendments to strategic significance.
• The onsite biodiversity value must include all habitat within the submitted redline boundary, including any area for proposed tree planting.
• The onsite biodiversity value will be determined by detailed soft landscaping plans. If the original consent is an outline application the reservation of matters for soft landscaping will need to be discharged before the final biodiversity value can be calculated (and a biodiversity gain plan submitted).
• Any proposed registered offsite biodiversity gains will need to be registered and allocated to the development before the Biodiversity Gain Plan can be discharged.
• The proposed use of Statutory Biodiversity Credits should be agreed with EDDC prior to the submission of a biodiversity gain plan, unless <0.25 biodiversity units are required.
• Once a biodiversity gain plan has been approved, it cannot be amended, unless a new biodiversity gain plan is submitted.

Is a fee required to apply to discharge the statutory Biodiversity Gain Plan condition?

• Yes, a fee is payable, currently £298 (as of April 2025).
• If the discharge of the Gain Plan forms part of the same discharge of condition application as other conditions on the planning permission, a single fee is paid.
• If the discharge of condition application for the Gain Plan is submitted separately to other conditions a separate, additional fee is required.

In other words, the fees are the same as for other condition discharges where the fee is per application and a single application can be for a single condition or multiple conditions.

If there are conditions requiring a LEMP and/or HMMP as well as the Biodiversity Gain Plan, it is recommended that you seek to discharge all of these at the same time as they are likely to be linked.

Statutory Biodiversity Metric Condition Assessments – what are they, why are they needed and how do I submit the forms?

Every habitat parcel onsite pre-development must be assessed by a competent person and assigned a habitat condition (with some exceptions). This is done using Defra Statutory Metric Condition Assessment Forms, a Microsoft Excel format spreadsheet. These assessments must be undertaken in the optimal time of year. 

Each habitat recorded within the metric must be accompanied by a condition assessment form (unless not applicable within the metric) and should include the following information:

• Site name and location
• Survey date and surveyor name
• Habitat parcel reference which should correspond to the reference number within the metric

These forms can be included as part of an ecological report. If sent separately, please submit the forms in pdf format.

Note – condition assessments are not required when using the Small Sites Metric as the condition is automatically assigned 

What is a Biodiversity Gain Site?

This is a site which has been or is in the process of being specifically developed to enhance and/or create habitats mainly for the purpose of fulfilling the BNG planning condition for another development. These sites must be secured by a legal agreement (either a section 106 with the LPA or a conservation covenant with a responsible body) and must be registered on the Natural England Biodiversity Gain Site register.

What exactly does ‘de minimis’ mean in relation to mandatory Biodiversity Net Gain?

A development site is exempt from mandatory BNG if the proposals impact the following:

• an area habitat that is less than 25m² (5m by 5m) AND is not a priority habitat
• a linear habitat (i.e. ornamental hedgerow) that is less than 5 m AND is not a priority habitat

Area habitat examples: grassland, pasture, arable field, bare ground, vacant or derelict land, scrub.

Priority habitat examples: native hedgerows, wood pasture and parkland, lowland mixed deciduous woodland, wet woodland, traditional orchards, lowland heathland, reedbeds, rivers and ponds, including other habitats of Principal Importance listed under Section 41 of the Natural Environment and Rural Communities Act 2006.

What information must be provided if you believe your development proposal is considered to be within scope of the 'de minimis' exemption?

When providing reasons for the 'de minimis' exemption, the applicant should provide sufficient evidence to support their justification. In cases where the development impacts an area smaller than 25 m², the following may be sufficient evidence:

• description of development proposals,
• existing and proposed site plans (supported by aerial photographs if relevant), and
• the area size of the development (in square metres)

Where it cannot be clearly demonstrated through site plans and descriptions whether an onsite habitat would be lost or degraded by the development, applicants are strongly encouraged to provide a completed metric for the pre-development and post-development value for the onsite habitat and clear plans identifying the nature and size of this pre-development onsite habitat and how much of it will be impacted by the development.

Further guidance on the de minimis exemption can be found in De Minimis Exemption (BNG) PAS Advice Note.

What if my development proposals will only have a temporary impact to the habitats onsite?

If you believe your development proposals will only have a temporary impact (i.e., a decrease in biodiversity value) to any baseline habitat(s), and your application is liable for mandatory Biodiversity Net Gain, then the following considerations apply:

• This is NOT an exemption from the Biodiversity Net Gain condition. You must still undertake a BNG assessment and provide a Metric calculation (using either the Statutory Biodiversity Metric or the Small Sites Metric)
• In accordance with the Statutory Biodiversity Metric User Guide, a temporary impact to a habitat is when this habitat will be restored to the following:
  • • The baseline habitat type within two years of the initial impact; AND
    • The baseline condition within two years of the initial impact
• The habitat in question is recorded within the Metric as ‘retained’
• You must submit sufficient evidence to the LPA to support your belief the impact is temporary and can be restored to its baseline type/condition within two years

What does Metric Rule 4 entail, and in what situations is it applicable?

This rule applies only in cases where there is a clear ecological justification that a proposal will deliver significant environmental benefits not fully captured by the metric tool. The LPA will only permit the use of Rule 4 in cases where exceptional ecological circumstances are justified and evidenced.

Detailed guidance can be found in Rule 4 (BNG) PAS Advice Note Nov 2025

When do I need to request a soil survey for a habitat bank or planning application that I am submitting?

The plant assemblages that grow in any given location are determined by a number of environmental factors including climate and management and also the ground conditions, soil nutrients and pH.

An understanding of current soil parameters on a site is essential to determine the feasibility and ultimately, the likely success of any proposed grassland enhancement, restoration or creation project.

For all off-site and on-site BNG grassland habitat that is of medium distinctiveness or above (in the BNG statutory metric) and is to be of moderate condition or above should have a soil assessment undertaken to determine the nutrient levels present.

Please refer to Guidance on Soils for Grassland Enhancement, Restoration and Creation as part of BNG proposals (DCC, Feb 2025).

Are Outline Planning Applications in scope for Biodiversity Net Gain?

Unless exempt for another reason, all outline planning applications will be subject to the general biodiversity gain condition at the point of application submission - not at the reserved matters stage

Do we need to provide any general biodiversity enhancements in addition to Biodiversity Net Gain?

Biodiversity Net Gain only relates to habitats and therefore, does not provide specific enhancements for species. For that reason, species assessments should still be undertaken as appropriate and biodiversity enhancements such as bat boxes, bird boxes, swift bricks, bee bricks, insect hotels, hedgehog gaps in fencing, native wildflower planting and other features, should be provided where they will enhance the value of the site for wildlife.