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Biodiversity Net Gain

The final biodiversity net gain (BNG) regulations have been laid before parliament and, following the usual parliamentary process, BNG became mandatory for new major developments (unless exempt) on Monday 12th of February 2024 and all minor developments (unless exempt) from 2nd April 2024. All new developments now have to deliver net gains for biodiversity leading to positive outcomes for nature, better places for local communities and more consistent and transparent requirements for developers.

Which types of development will BNG apply to?

BNG will apply to new applications for planning permission, except for applications for retrospective permission. Further exemptions can be found on the following Government websiteBNG Exempt Developments (opens new window)

Where you consider a development is exempt then your application must be accompanied by a statement setting out why you think your development is exempt, quoting the relevant parts of the Regulations

Applications made under any other route, for example deemed permissions under section 90 TCPA 1990 or permission granted by a Local Development Order, will not be subject to mandatory BNG yet. Further regulations will be required to modify the procedure for these other routes to planning permission. Details regarding these further regulations are expected to be released in due course.

Self Build Exemption

If you are claiming an exemption under the self-build category.  Please follow these steps before making an application for Planning Permission:

1. Ensure your proposal falls within the definition of the Self-build and Custom Housebuilding Act 2015 shown below:

In this Act "self-build and custom housebuilding" means the building or completion by—

(a) individuals,

(b) associations of individuals, or

(c) persons working with or for individuals or associations of individuals, of houses to be occupied as homes by those individuals.

(A2) But it does not include the building of a house on a plot acquired from a person who builds the house wholly or mainly to plans or specifications decided or offered by that person.

2. Ensure your development meets the exemption criteria of:

(a) consists of no more than 9 dwellings

(b) on a site that has an area no larger than 0.5 hectares    

3. Ensure the owner of the home has had the primary input into the design and layout of the dwelling.  You will be asked to demonstrate this through your submission for Planning Permission and this should include (but not limited to) a written statement setting out how the self-builder has had input into the design and layout of the home, where and what parts of the process, inspiration and how this has been executed/evolved, details of meetings, details of sufficient funds to build (i.e. self-build mortgage agreement) and a design and engagement brief setting out how the relevant parties will work together to deliver the project. 

4. Ideally the person promoting the plot should be included on the Authority's Self Build Register at the time of applying for planning permission.

5. The description of development must include 'self-build' within its title.

Applications which fail to include the aforementioned information will not be validated (unless a relevant BNG metric is submitted) in accordance with the Council's Local List (PDF, 820 KB)(opens new window)

Please note a legal obligation will be required to secure the development as a Self-Build

If you are developing a site with one self build dwelling, the Council have produced a standard form undertakings (Word doc, 32 KB)(opens new window) for your use together with guidance notes (PDF, 196 KB)(opens new window).  Please note it is not to be used for multiple units.  

With self build developments, it is likely you will also need to pay Norfolk RAMs.  Further information regarding this can be found on ourNorfolk RAMs web page.  A joint Unilateral undertaking for both self-build and Norfolk RAMs has been created for this purpose together with guidance notes.

It is recommended that the proposed undertaking (updated in accordance with the guidance notes) is submitted electronically via email with your application at validation stage together with evidence of ownership.  Once the proposed undertaking is approved by the Council you should send the signed agreement with plan attached to the Case Officer.  Any changes to the standard form other than in accordance with the guidance notes will require legal approval and will incur additional legal fees payable by you.  It is therefore strongly recommended that the guidance notes are followed carefully and no amendments are made other than as directed in the guidance. 

In order to process the Unilateral Undertaking, the Local Planning Authority charge an administration fee (non-refundable) and monitoring fee to collect, monitor and issue the tariff. The administration fee is £100 and an additional £150 monitoring fee per application is also required. The administration and monitoring fees are to be paid within 10 days of your planning application being validated. 

A £100 title plan check fee is also required to ensure you have a legal right to sign the agreement. With this you must provide evidence of title to the application site.  The title check fee relates to the time incurred by the Council's planning lawyer in reviewing title and verifying that the document will bind the land, not the Land Registry fee.  This is necessary to ensure that obligations are enforceable

For more than one self-build plot a bespoke s.106 will be required for which you will need to enter into negations with the Council's solicitor to ensure appropriate drafting, to secure the required plots as self-build.

Transitional Arrangements

BNG will only apply where the planning application was made on or after the 12th of February 2024 for major applications, or the 2nd of April 2024 for minor applications.

'Made' means the application must have been valid before the 12th of February 2024 for major applications and before the 2nd of April 2024 for minor applications.  Failure to submit a valid application before these dates will mean additional validation requirements, including the BNG statement and metric and at least 10% BNG to be delivered, as per the regulations.

Calculate biodiversity value with the statutory biodiversity metric (opens new window)

These transitional arrangements also mean that if you received planning permission before the 12th of February, and that permission wasn't subject to BNG, if you then apply via section 73 to vary a planning condition on that permission, the new permission granted under section 73 would also be exempt from BNG.

If a planning application for a small site development was made during the small sites extended transition period, between the 12th of February and the 2nd of April 2024, and subsequently a section 73 variation was granted after the 2nd of April, the same transitional arrangements will apply and BNG will not be required on any subsequent section 73 variations.

Advice to applicants and agents

There is a lot of advice available on the GOV.UK website and aBiodiversity Net Gain step by step guide for developers (opens new window) 

Please note the Council are unable to assist with queries about BNG or completing the metric, you will need to engage with a suitably qualified ecologist, as set out in the Regulations. 


Further information can be found in the following regulations:

The Biodiversity Gain (Town and Country Planning) (Modifications and Amendments) (England) Regulations 2024 (opens new window)

The Biodiversity Gain Requirements (Exemptions) Regulations 2024 (opens new window)

The Biodiversity Gain Requirements (Irreplaceable Habitat) Regulations 2024 (opens new window)

The Biodiversity Gain Site Register Regulations 2024 (opens new window)

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Last modified on 03 October 2025