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Planning practice advice on biodiversity net gain (BNG) which is an approach to development that aims to leave the natural environment in a measurably better state than before.

The statutory framework for securing BNG is a pre-commencement condition known as the general biodiversity gain condition. Once planning permission has been granted, a biodiversity gain plan must be submitted and approved by the planning authority before the start of the development. It requires a commitment by the developer to provide a minimum of 10% BNG for at least 30 years.

Which types of developments will BNG apply to?

All planning permissions, except where exempt, must deliver a BNG of at least 10%, demonstrated using a biodiversity metric and providing a biodiversity gain plan.

Major developments

Major developments include:

residential developments with ten or more dwellings
residential development on a site having an area of 0.5 hectares or more
buildings creating more than 1,000m2 or more of a commercial floorspace
development on a site having an area of 1 hectare or more.

Major developments will need to use the statutory metric.

Small developments

Small developments include either of the following:

residential developments of 1 and 9 dwellings or the site area less than 0.5 hectares if unknown
commercial development where floor space is less than 1,000m2 or the total site area is less than 1 hectare

Small developments must use the Small Sites Metric (SSM) where specific criteria are met. Where:

only habitats available in the SSM are present onsite
no priority habitats are present onsite
no statutory protected sites or habitats are present, and no European-protected species are present

Should the above criteria not be met, the statutory metric must support the application.

Developments exempt from BNG

Details of developments considered exempt from mandatory BNG have been published at Biodiversity Net Gain - what are the exemptions? When the applicant believes that the development is exempt from the biodiversity gain condition, they must provide a statement explaining the reasons for the exemption.

When will BNG become mandatory?

The below timescales indicate when BNG will become mandatory for different types of development. Applications made before these dates are not subject to biodiversity net gain.

Development type	Required from
Major developments¹	12 February 2024
Small developments¹	2 April 2024
Nationally significant infrastructure projects	November 2025 (to be confirmed)

Biodiversity gain hierarchy

Developers must demonstrate compliance with the biodiversity gain hierarchy by completing the following actions in order of priority:

Avoiding adverse effects of the development on onsite habitat with a habitat distinctiveness score, applied in the biodiversity metric, equal to or higher than six.

So far as:

those adverse effects cannot be avoided, mitigating those effects
those adverse effects cannot be mitigated, habitat enhancement of onsite habitat
there cannot be that enhancement, creation of onsite habitat
there cannot be that creation, the availability of registered offsite biodiversity gain
that offsite habitat enhancement cannot be secured, purchasing biodiversity credits

Developers are encouraged to follow the biodiversity gain hierarchy from the earliest stage possible when selecting a site and considering development proposals.

Local planning authorities must consider the biodiversity gain hierarchy when considering whether the biodiversity objective has been met and whether to approve the biodiversity gain plan.

Delivery of 10% BNG

There are three ways a developer can achieve 10% BNG:

They can enhance and restore biodiversity onsite within the red line boundary of a development site.
If developers can only achieve part of their BNG onsite, they can deliver through a mixture of onsite and offsite. Developers can either make offsite biodiversity gains on their land outside the development site or buy offsite biodiversity units on the market.
If developers cannot achieve onsite or offsite BNG, they must buy statutory biodiversity credits from the government. It must be a last resort. The government will use the revenue to invest in habitat creation in England.

Developers can combine all three options but must follow the steps to comply with the biodiversity gain hierarchy.

BNG cannot be delivered where irreplaceable habitats are lost. The secondary legislation which defines irreplaceable habitats is available here: The Biodiversity Gain Requirements (Irreplaceable Habitat).

Habitats enhanced or created as part of BNG will be secured via planning conditions (onsite habitats), legal obligations, or conservation covenants ('significant' onsite provisions and offsite habitats, including those purchased as biodiversity credits).

Further advice and guidance

Meet biodiversity net gain requirements: steps for developers - GOV.UK .

Future Homes Hub UK has launched a free and independent online finder for biodiversity units that you can search by local planning authority or National Character Area.

How to demonstrate BNG as part of an application

Where development would be subject to the general biodiversity gain condition, the application must be accompanied by the following minimum information ³:

A statement as to whether the applicant believes that planning permission, if granted, would be subject to the biodiversity gain condition.
The pre-development biodiversity value of the onsite habitat on the date of application (or an earlier date), including the completed metric calculation tool used, showing the calculations, the publication date and the version of the biodiversity metric used to calculate that value.
Where the applicant wishes to use an earlier date, the proposed date, and the reasons for suggesting that date.
A statement confirming whether the biodiversity value of the onsite habitat is lower on the date of application (or an earlier date) because of the carrying on of activities ('degradation'). In which case, the value is to be taken as immediately before the carrying on of the activities, and if degradation has taken place, supporting evidence of this.
Description of any irreplaceable habitat² on the land to which the application relates that exists on the date of application or an earlier date.
A plan drawn to an identified scale which must show the direction of North, showing onsite habitat existing on the date of application or an earlier date, including any irreplaceable habitat.

The local planning authority will only accept applications that provide this information.

Biodiversity gain statement template

We have provided a biodiversity gain statement template to be submitted to support applications to ensure this information has been provided to minimise the risk of your application being rejected. The relevant biodiversity metric should accompany this.

In addition to the minimum information requirements, further information may need to be provided to assist the consideration of biodiversity net gain as part of the planning application, especially where there are particular considerations around significant onsite biodiversity enhancements or use of offsite biodiversity gains.

We have allowed such information to be provided in our biodiversity gain statement template. We would appreciate completing as many details as possible to minimise the risk of delays to an application. It is beneficial to consider BNG as early in the design stages as possible and provide more than the statutory minimum information.

Phased developments

A biodiversity gain plan must be submitted and approved by the planning authority before any development can begin.
A phase biodiversity gain plan for each phase must be submitted and approved by the planning authority before the development of that phase can begin. This plan will set out a phase's contribution to biodiversity net gain and track progress towards the overall biodiversity gain objective.

Determining a planning application

When determining applications, the local planning authority will adhere to the PPG and standing advice.

We may request the following information:

information about any potential planning obligations such as S106 agreements, including any funding arrangements to deliver or monitor BNG
draft Habitat Management and Monitoring Plan (consistent with Natural England's Habitat Management and Monitoring Plan template)
Ecological Impact Assessment (EcIA) and up to date ecological surveys
protected species licensing consideration

A developer may want to submit a draft plan alongside the planning application for information and discuss this plan with the local planning authority before determining the application. However, this is not a minimum information requirement.

General planning condition

Every grant of planning permission (excluding where an exemption applies) is deemed to have been granted subject to a general biodiversity gain condition to secure the biodiversity gain objective. It is a pre-commencement condition, which means that once planning permission has been granted, a biodiversity gain plan must be submitted and approved by the planning authority before the start of the development.

The general planning condition cannot be changed or removed.

It is crucial to consider biodiversity net gain throughout the planning process to meet the objective of gaining biodiversity and discharging the condition successfully.

The following BNG Best Practice Process Flow (Future Homes and PAS) illustrates how BNG can be considered at all stages of the process.

Applicants are encouraged to discuss biodiversity net gain requirements upfront using the pre-application advice service.

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