2021
November 2021
Environment Act receives Royal Assent
The primary legislation establishing mandatory BNG in England. Amends the Town and Country Planning Act 1990 via Schedule 7A to require 10% net gain. Also creates conservation covenants (Part 7) and provisions for extending BNG to NSIPs.
2022
September 2022
Conservation covenants available
Part 7 of the Environment Act comes into force. Landowners can now enter into conservation covenant agreements with designated responsible bodies. DEFRA begins accepting responsible body designation applications.
2023
July 2023
Statutory credit prices published
DEFRA publishes indicative prices for statutory biodiversity credits, starting at £42,000 per credit for common habitats up to £650,000 for rare habitats. The 2x spatial risk multiplier is confirmed.
November 2023
Statutory Biodiversity Metric 4.0 published
DEFRA publishes the mandatory Statutory Biodiversity Metric — the calculation tool that must be used for all BNG assessments. Distributed as an Excel spreadsheet (.xlsm) with user guides and the Small Sites Metric.
2024
12 February 2024
BNG mandatory for major developments
Biodiversity Net Gain becomes a statutory planning condition for major developments in England. All major planning applications submitted from this date must demonstrate 10% net gain.
2 April 2024
BNG mandatory for small sites
BNG requirements extended to small site developments, completing the rollout to virtually all planning applications in England (subject to exemptions).
September 2024
Bramford to Twinstead DCO decision
The Secretary of State supports National Grid's voluntary 10% BNG commitment in a DCO decision, granting compulsory purchase powers for BNG delivery land — setting a precedent for voluntary NSIP BNG.
2025
January 2025
Environmental Improvement Plan 2025
Confirms BNG will become mandatory for Nationally Significant Infrastructure Projects from May 2026, alongside broader environmental targets.
May 2025
NSIP BNG consultation opens
Government consultation on the detailed framework for NSIP BNG, including treatment of order limits, temporary land use, phased delivery, and the biodiversity gain statement. Closes July 2025.
June 2025
NSIP start date delayed to May 2026
DEFRA postpones the NSIP BNG start date from November 2025 to May 2026, to allow more time for a clear framework.
Summer 2025
BNG implementation consultation
Government consults on improving BNG implementation for minor, medium, and brownfield developments. Options include changes to exemptions, simplified compliance routes, and trading rule adjustments.
16 December 2025
0.2 hectare exemption confirmed
The Housing Secretary announces a new area-based exemption for sites under 0.2 hectares, measures to streamline off-site delivery, and a forthcoming consultation on a targeted brownfield exemption for residential sites up to 2.5 hectares.
2026
12 February 2026
BNG marks its second anniversary
Two years of mandatory BNG: 197 registered gain sites, ~28,000 units available, ~1,500 sold, 107 of 309 LPAs with habitat banks. The market is maturing but significant geographic gaps remain.
15 April 2026
Defra confirms three BNG reforms
Defra publishes its consultation response confirming: NSIP BNG go-live 2 November 2026; a package of new exemptions (0.2ha area-based threshold, self-build removal, temporary planning permissions, biodiversity-led developments, parks and playing fields, equal-status off-site delivery for minor residential schemes) to come into force before 31 July 2026; and the opening of a brownfield residential exemption consultation. See our 2026 reforms guide.
10 June 2026
Brownfield residential exemption consultation closes
Rapid consultation on a targeted BNG exemption for residential brownfield sites of 0.5–2.5 hectares meeting a 75% previously-developed land definition. Closes 10 June 2026. The consultation also covers a potential review of the open mosaic habitat definition and trading rules.
Before 31 July 2026
0.2 hectare exemption and simplified compliance routes take effect
The new area-based exemption replaces the 25 sqm threshold — sites under 0.2 hectares no longer need to deliver BNG (priority habitats excepted). The self-build exemption is removed (most projects now covered by the 0.2ha threshold). Equal-status off-site delivery for minor residential schemes (9 or fewer dwellings on sites ≤1ha) also takes effect.
31 July 2026
Long-stop: first tranche of secondary legislation
Secondary legislation introducing the 0.2ha area-based exemption, removal of the self-build exemption, temporary planning permission exemption, and equal-status off-site delivery for minor developments is expected in force by this date.
2 November 2026
BNG mandatory for NSIPs
Nationally Significant Infrastructure Projects must deliver 10% BNG from this date — confirmed by Defra on 15 April 2026. The regime uses targeted BNG boundaries (only negatively-affected habitats assessed), off-site units can be sourced from anywhere within the NSIP BNG boundary without a spatial risk multiplier penalty, and a biodiversity gain plan must be submitted alongside the DCO application. Not retrospective: applications submitted before 2 November 2026 are excluded.
Throughout 2026
LNRS adoption completes
The remaining Local Nature Recovery Strategies are expected to be adopted across England, completing national coverage and strengthening the strategic significance multiplier in the metric.
2026–2027
2026–2027
NPPF changes
Proposed changes to the National Planning Policy Framework may restrict LPAs from requiring above 10% BNG through local plans, and give greater weight to LNRS in plan-making and decision-making.
For the full detail on all 2026 changes, see our 2026 reforms guide.