Government Consults On Improving Implementation of Biodiversity Net Gain

Government consults on improving implementation of biodiversity net gain (BNG) for minor, medium and brownfield development

On 28 May 2025, the Department for Environment, Food and Rural Affairs published a consultation on the implementation of biodiversity net gain (BNG) for minor, medium and brownfield development.

The consultation includes proposals to:

• Extend exemptions from BNG. The consultation proposes making targeted revisions to the existing exemptions, introducing a full exemption for all minor developments or introducing additional exemptions (which could apply alongside the other options).
• Simplify the small sites metric (SSM). The consultation proposes renaming the SSM to the “low impact metric” and using it on sites that are less than one hectare in size where no priority habitats are present. This would extend the revised SSM to apply to the proposed “medium” category of development as well as the minor category. The consultation proposes either removing or amending the SSM trading rules, changing where the SSM habitat condition is fixed, merging some habitat categories and improving competency requirements. The consultation also proposes digitising future versions of the SSM and the main metric tool (both are currently in Excel format).
• Increase accessibility of the off-site market. The consultation proposes relaxing the requirement for planning authorities to prioritise on-site over off-site compensation when applying the biodiversity gain hierarchy (for minor development only). It seeks views on disapplying the spatial risk multiplier for minor developments purchasing off-site units or using local nature recovery strategy areas alongside national character areas instead of local planning authority boundaries when applying the spatial risk multiplier.
• Address challenges for brownfield developments. The consultation includes proposals relating to open mosaic habitat.

Annex A to the consultation contains a table summarising the proposals. The consultation closes on 24 July 2025.

Also on 28 May 2025, the government published a consultation on implementing BNG for nationally significant infrastructure projects (NSIPs) and a working paper on reforming site thresholds for residential development. The latter refers to streamlining BNG requirements for minor residential developments (sites under ten dwellings or less than 0.5 hectare if no number is known) and simplifying BNG requirements for a new category of medium developments (between ten and 49 dwellings, and the site is less than one hectare (or sites between 0.5 and one hectare if no number is known)