Biodiversity net gain (BNG) is an approach to development, and/or land management which mandates developers to deliver measurable improvements for biodiversity by creating or enhancing habitats in association with development. Biodiversity net gain can be achieved on-site, off-site or through a combination of on-site and off-site measures. In England, Mandatory BNG, requiring a 10% net gain in biodiversity, will apply to most developments from November 2023, unless exempt. It will apply to small sites from April 2024.