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| 3 minutes read

Biodiversity Net Gain is expected in November 2023, are you ready?

Biodiversity Net Gain- the countdown is on

From November 2023 (subject to Regulations being made) planning permissions will be granted subject to a mandatory condition to secure habitat improvements that amount to a 10% Biodiversity Net Gain (BNG) over the baseline habitat value of the site. 

Assessing and enhancing BNG during development process aims to leave biodiversity in a better state than it was before development.


The State of Nature Reports published by the State of Nature Partnership presents an overview of how the country’s wildlife is fairing.  The 2019 report suggests that despite legislation and policy to protect biodiversity, there has been a 13% decline in the average abundance of wildlife in the UK since the 1970. BNG aims to create new habitat as well as enhance existing habitats.

The Government announced it would mandate net gains for biodiversity in the 2019 Spring Statement and subsequently published a consultation on the proposals in 2022.

Government guidance published in response to the consultation findings explains that developers must try to avoid loss of habitat on land being developed.  Where this cannot be achieved, then habitat should be created either on site – delivered through landscaping and green infrastructure or, off site through habitat creation enhancement including through habitat banks or by statutory credits.  All three options can be combined to deliver BNG.

What does BNG mean for developers and landowners?

BNG is not a new concept and is already embedded in the National Planning Policy Framework (NPPF).  The NPPF provides that in determining planning applications local planning authorities should apply principles which include supporting development whose primary objective is to conserve or enhance biodiversity.

From November 2023 planning permissions in England will be subject to a deemed planning condition which provides that development cannot commence until the developer has submitted a Biodiversity Gain Plan and the local planning authority has approved it.

The purpose of the deemed condition is to ensure that the biodiversity value attributable to the development exceeds the pre-development biodiversity value of the onsite habitat by at least 10% and is maintained for a period of 30 years.

Small sites will be exempted from the requirement, at least until further Regulations are made in 2024. BNG requirements will not apply to permitted development, household applications and sites which are being enhanced.

How will BNG be measured?

The Environment Act 2021 requires the Secretary of State to consult on the biodiversity metric for measuring BNG, which score different habitat types based on their relative value to wildlife. 

Following consultation Defra confirmed in March 2023 that BNG will be using Natural England’s biodiversity metric 4.0. 

The metric is used to measure biodiversity losses and gains. The metric can be used to calculate how a development, or a change in land management, will change the biodiversity value of a site. Four key factors underpin this comparison: habitat size; condition; distinctiveness; and location.

What steps do developers and landowners need to take to prepare for BNG in their development proposals?

NPPF requirements mean that developers are likely to be familiar with the process of surveying, assessing ecology value and addressing any loss through, for instance, planning obligations to deliver net gain.

However, even the most experienced developer needs to consider blind spots in the market and development process to ensure that they can demonstrate the full compliance with BNG in their development plans. Consider:

  • Do you have your profession team lined up?  The evidence base for calculating the biodiversity metric is complex and specific to each site.  You will need a competent person (usually an ecologist) to provide advice on the sites value, the Biodiversity Gain Plan and long term site management.
  • Is your development multi-phased? If so, your application will need to explain your strategy to achieve BNG across the whole site and how this will be delivered over time.

It has been widely reported that BNG may be more effectively achieved through on site or local habitat improvement, as opposed to buying credits.  So knowing the ecological value of the area surrounding your proposed development site should become a key part of the your due diligence process.


  • BNG is undoubtedly an opportunity for landowners who have land available and:
  • are prepared to commit to managing the habitat for at least 30 years;
  • agree a habitat management and monitoring plan with the local planning authority,
  • enter into a planning obligation or conservation covenant to either do something or refrain from doing something for a conservation purpose. 
  • BNG sites don’t need to be large country estates.  Provided the criteria set out above are met existing open space and communal areas can be used for BNG.  Furthermore, biodiversity and nutrient credits (created to capture nutrients which would otherwise effect protected water bodies) can be created for the same piece of land and sold to developers.  Applications to register land for a BNG site begin in November 2023.
  • If you are considering using land for BNG and/or nitrate credits you should consider if there are any impediments such as restrictive covenants, third party rights, and funders requirements which might prevent this.  Take appropriate advice before applying to register it.


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