0.2ha small-site exemption
For applications submitted on or after 6 Aug 2026, development on a site of no more than 0.2 hectares is exempt from the mandatory 10% BNG requirement, provided the development would not affect an on-site priority habitat [Biodiversity Gain (T&CP) (Amendments and Transitional Provisions) (England) Regs 2026 (SI 2026/790)]. The 0.2ha threshold is measured against the whole site within the application red-line boundary, not just the development footprint or the area of habitat affected.
Self and custom-build exemption removed
The separate exemption for self and custom-build development is removed for applications submitted on or after 6 Aug 2026. Many smaller self-build schemes will instead fall within the new area-based 0.2ha exemption, but that is not automatic; the site area and priority-habitat tests decide. S106 drafting for self-build schemes should no longer rely on the old dedicated exemption.
Relaxed hierarchy for non-major development
For development that is not major development, the biodiversity gain hierarchy is relaxed so that on-site habitat creation and enhancement and registered off-site gains sit at the same level of preference, rather than off-site sitting below on-site. This gives smaller schemes more flexibility in how they discharge the requirement.
NSIP deferral to Nov 2026
Biodiversity net gain for Nationally Significant Infrastructure Projects is deferred, with mandatory application from Nov 2026. Promoters working on DCO applications in 2026 should confirm the commencement position against the current Defra guidance.
LPA drafting implications
For applications from 6 Aug 2026, LPAs apply the amended regime above; earlier applications keep the Feb 2024 requirement. Where a scheme is close to the 0.2ha line or may affect a priority habitat, S106 drafting should retain the BNG clause and the 30-year management plan so the obligation stands if the exemption does not apply.