Biodiversity Net Gain (BNG) in England is a regulatory framework designed to ensure that new developments enhance biodiversity by at least 10%. This framework is mandatory for most new developments from February 12, 2024, and aims to improve wildlife habitats and contribute to nature's recovery.

1. Mandatory BNG Requirements:

   • Developers must achieve at least a 10% net gain in biodiversity. This can be done on-site, off-site, or through purchasing biodiversity credits from the government as a last resort.

     A biodiversity gain plan must be submitted and approved before development can commence. This plan should detail how the biodiversity net gain will be achieved and maintained for at least 30 years​ (GOV.UK)​​ (Gov UK Environment)​

2. Exemptions:

   • Certain types of development are exempt from the BNG requirement, including householder developments, some temporary developments, urgent Crown developments, and small-scale developments that meet specific criteria (e.g., impacting less than 25 square meters of habitat).

   • These exemptions are designed to keep the policy proportionate while still ambitious​ (GOV.UK)​​ (GOV.UK)​.

3. Compliance Process:

   • Developers must assess the pre-development biodiversity value using a statutory biodiversity metric and outline steps to achieve the required net gain. This involves avoiding loss of habitats where possible, creating or enhancing habitats, and potentially buying off-site biodiversity units if on-site measures are insufficient.

   • The biodiversity gain plan must be submitted with the planning application and approved by the local planning authority (LPA) within eight weeks unless an alternative period is agreed upon. Failure to meet BNG requirements can result in enforcement actions by the LPA​ (GOV.UK)​​ (Gov UK Environment)​.

4. Biodiversity Gain Site Register:

   • Off-site biodiversity gains must be recorded in a publicly accessible biodiversity gain site register managed by Natural England. This register ensures transparency and accountability for off-site biodiversity commitments​ (Gov UK Environment)​.

5. Long-term Management:

   • Both on-site and off-site habitats created or enhanced for BNG must be maintained for a minimum of 30 years. This responsibility falls on the landowner or the developer, depending on the specific arrangements detailed in legal agreements​ (GOV.UK)​.

6. Irreplaceable Habitats:

   • Certain habitats deemed irreplaceable are subject to specific protections and require bespoke compensation agreements rather than the standard 10% net gain. These habitats have significant protections under existing frameworks, which BNG regulations further reinforce​ (Gov UK Environment)​.

Overall, BNG represents a significant shift in planning policy aimed at integrating biodiversity conservation into the development process, ensuring that the natural environment is better off as a result of new developments.