Biodiversity Net Gain (BNG)

There is a national set of validation requirements for applications where BNG applies.

Development subject to the BNG Condition

Where development would be subject to the general biodiversity gain condition, the application must, as a minimum, be accompanied by the following information set out in Article 7 of the 'Town and Country Planning (Development Management Procedure) (England) Order 2015':

• A statement as to whether the applicant believes the planning permission, if granted, would be subject to the biodiversity gain condition;
• The pre-development biodiversity value of the on-site habitat on the date of application (or an earlier date) including the completed metric calculation tool showing the calculations, the publication date and version of the biodiversity metric used to calculate that value;
• Where the applicant wishes to use an earlier date, the proposed earlier date and the reasons for proposing that date;
• A statement whether activities have been carried out prior to the date of application (or earlier proposed date), that result in loss of onsite biodiversity value (‘degradation’), and where they have:
  • a statement to the effect that these activities have been carried out;
  • the date immediately before these activities were carried out;
  • the pre-development biodiversity value of the onsite habitat on this date;
  • the completed metric calculation tool showing the calculations, and
  • any available supporting evidence of this;
• A description of any irreplaceable habitat (as set out in column 1 of the Schedule to the Biodiversity Gain Requirements (Irreplaceable Habitat) Regulations [2024]) on the land to which the application relates, that exists on the date of application, (or an earlier date); and
• A plan, drawn to an identified scale which must show the direction of North, showing on-site habitat existing on the date of application (or an earlier date), including any irreplaceable habitat.

If this information has not been provided, the Local Planning Authority (LPA) will be unable to validate the application.

There are specific exemptions from Biodiversity Net Gain for certain types of development.

An applicant is expected to provide a statement to set out what exemption(s) or transitional provision(s) apply to the development. The planning application form includes space for this statement.

The biodiversity gain condition does not apply to the following types of development:

• Retrospective planning permissions made under section 73A.
• Section 73 permissions (removal or variation of condition/s) where the original permission which the section 73 relates to was either granted before 12 February 2024 or the application for the original permission was made before 12 February 2024. This is referred to as transitional provision(s) in national legislation.
• Householder development as defined within Article 2(1) of the Town and Country Planning (Development Management Procedure) (England) Order 2015.
• Development granted planning permission by a development order under section 59. This includes permitted development rights (Certificates of Lawful Development and Prior Approval applications).
• Development subject to the de minimis exemption. Development that does not impact a priority habitat and impacts less than 25 square metres (e.g. 5m by 5m) of on-site habitat, or 5 metres of linear habitats such as hedgerows.
• Self-build and custom build development. You must meet all of the following conditions to qualify for an exemption as a self-build or custom build. The development must:
  • consist of no more than 9 dwellings
  • be on a site that has an area no larger than 0.5 hectares
  • consist exclusively of dwellings that are self-build or custom housebuilding as defined in section 1(A1) of the Self-build and Custom Housebuilding Act 2015. Find out more about what qualifies as self-build and custom housebuilding.
• Urgent Crown development granted permission under section 293A of the Town and Country Planning Act 1990.
• Development of a biodiversity gain site. Development which is undertaken solely or mainly for the purpose of fulfilling, in whole or in part, the biodiversity gain condition which applies in relation to another development.
• Development related to the high-speed railway transport network. Development forming part of, or ancillary to, the high speed railway transport network comprising connections between all or any of the places or parts of the transport network specified in section 1(2) of the High Speed Rail (Preparation) Act 2013.
• Biodiversity Net Gain does not apply to listed building consent applications. But please note that if these are made jointly with a full application which is not exempt from Biodiversity Net Gain, then Biodiversity Net Gain will be required for the full application.
• The approval of reserved matters for outline planning permissions is not subject to the biodiversity gain condition (as it is not a grant of planning permission).

The exemptions above are set out in paragraph 17 of Schedule 7A of the Town and Country Planning Act 1990 and the Biodiversity Gain Requirements (Exemptions) Regulations 2024.

If the LPA grants planning permission for a development that is applicable for BNG, the developer must submit a Biodiversity Gain Plan prior to the commencement of development. The fee for that application is £145.

The Biodiversity Gain Plan sets out how the biodiversity gain objective of at least a 10% gain will be met for the development granted planning permission.

A developer may want to submit a draft plan for information at the pre-application or planning application stage, although this is not a national information requirement.

Using the Biodiversity Gain Plan template is strongly encouraged to bring together the required information into one document for approval.

Appeals may be made at any time within 6 months of the decision on the Biodiversity Gain Plan or, if no decision has been made, within 6 months from when a decision should have been given.

All off-site gains must be published on the Biodiversity Gain Site register. Developers cannot start work on a development and the LPA cannot publish a development on the Biodiversity Gain Site register until the LPA has approved the biodiversity gain plan.

Compensatory measures will only be considered when no other measures are demonstrated to be feasible as set out in the Mitigation Hierarchy (image below).

Mitigation and compensation measures must offset any losses to achieve a measurable net gain for biodiversity.

An applicant can demonstrate compliance with the 10% BNG requirement in the following three ways. The preference is for applicants to meet it on-site as per option 1 and only where options 1 and 2 are shown to not be possible will option 3 be allowed.

1. On-Site: Developers can enhance and restore biodiversity on-site (within the red line boundary of a development site).
2. Off-site: If developers can only achieve part of their BNG on-site, they can deliver through a mixture of on-site and off-site. Developers can either make off-site biodiversity gains on their own land outside the development site or buy off-site biodiversity units on the market.
3. Purchasing Statutory Credits: If developers cannot achieve on-site or off-site BNG, they must buy statutory biodiversity credits from the government. It must be demonstrated that on-site and off-site habitat creation have been maximised.

Applicants must demonstrate that they’ve followed the BNG hierarchy. The adverse effect on the biodiversity should be compensated by prioritising in order, where possible, the enhancement of existing onsite habitats, creation of new onsite habitats, allocation of registered offsite gains and finally the purchase of biodiversity credits.

On-site gain

The baseline habitat unit score should be used to inform development layouts, to maximise ecological gains on-site.

It should be noted that a baseline date for degradation has been set for 30 January 2020. This means that any unauthorised works carried out after this date reduces the BNG value.

Private gardens

A private garden is a garden within the curtilage of a privately owned or tenanted dwelling house. Private gardens can contain important features for biodiversity, including mature trees and hedgerows.

When recording habitats at baseline within a private garden you may need to assess any important features as individual habitat parcels to avoid under-recording biodiversity. This may include:

• recording individual trees
• recording hedgerows
• recording other habitats, such as ponds

See more about which individual trees to record at baseline within private gardens.

The post-development private garden has no public access, and biodiversity net gains cannot be legally secured. As these gains cannot be secured you should only record created private gardens as either:

• 'urban - vegetated garden'; or
• 'urban - unvegetated garden'

You should not:

• record the creation of any other new habitats within private gardens
• 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.

Off-site gain

Where it is not possible to avoid or mitigate all impacts on site, an off-site Biodiversity Offset Agreement should be submitted.

Off-site means any biodiversity gains to be delivered on land outside of the red-line boundary of a development. Any land proposed for use for off-site BNG must be a registered biodiversity gain site.

To be eligible for registration on the gain site register, land must be secured by one of two legal mechanisms:

• planning obligation (section 106) with an LPA
• conservation covenant agreement with a responsible body

Currently, Watford Borough Council is not a responsible body, therefore the off-site gains must be secured through a S106 agreement.

As part of the legal agreement, you (or a third party you have sub-contracted to) will need to commit to:

• creating or enhancing habitats
• managing the habitats for at least 30 years

You should get legal advice before entering a legal agreement. You will have to pay for any legal or other costs related to the agreement.