BNG updates: a clearer, more proportionate framework — and a decisive shift for NSIPs
Defra’s April 2026 announcements confirm that Biodiversity Net Gain (BNG) is moving from early implementation into a more settled, workable regime.
The changes simplify requirements for small sites, widen what counts as “local” for off‑site delivery, and — for the first time — set out a clear, proportionate framework for applying BNG to Nationally Significant Infrastructure Projects (NSIPs). Together, these updates send a strong signal about how the off‑site BNG market is expected to function at scale.
Across the government blog and legal sector summaries, a consistent theme emerges: BNG is being refined, not diluted. The policy intent remains firm, but the rules are being adjusted to improve proportionality, market liquidity and alignment with Local Nature Recovery Strategies. For developers, land managers and habitat providers, the announcements bring greater certainty — particularly around spatial rules and the long‑anticipated extension of BNG to major infrastructure.
Changes happening soon (summer 2026)
1. New 0.2 hectare exemption for small sites –
All developments on sites of 0.2ha or less will be exempt from mandatory BNG, subject to safeguards for priority habitats.
Tip: This removes a large volume of very small, low‑unit transactions from the BNG system, allowing the market to focus on schemes with meaningful unit demand.
2. Removal of the self/custom‑build exemption –
The previous self‑build exemption will be withdrawn, with small schemes instead captured by the new 0.2ha threshold.
Tip: This simplifies exemptions and avoids having multiple parallel carve‑outs to interpret.
3. On‑site and off‑site delivery put on equal footing for minor development –
The biodiversity gain hierarchy will be relaxed so that minor developments are not forced into inappropriate on‑site solutions.
Tip: Expect increased acceptance of off‑site units for constrained or urban sites.
Changes to spatial rules and off‑site delivery geography
4. LNRS areas replace NCAs and LPA boundaries for spatial risk –
For terrestrial habitats, the spatial risk multiplier will now be assessed using
Local Nature Recovery Strategy (LNRS) areas only, not National Character Areas or local authority boundaries.
Tip: LNRS areas are much larger, meaning more off‑site options can qualify as “local” without penalty.
5. Spatial risk multiplier is retained, but applied differently –
The multiplier has
not been removed; it still applies where units are sourced outside the relevant LNRS area.
Tip: Location still matters—but the “local zone” is now wider and clearer.
Changes coming later in 2026
NSIP‑specific changes confirmed for late 2026
6. Mandatory BNG for NSIPs from 2 November 2026 –
All NSIP applications submitted from this date must deliver at least 10% BNG using the statutory metric.
Tip: This ends the voluntary / bespoke approaches previously used for major infrastructure.
7. Introduction of a defined “BNG boundary” for NSIPs –
BNG will apply only to habitats that are negatively impacted, or used to deliver BNG, within a defined BNG boundary — not the entire red‑line order limits.
Tip: This addresses proportionality and cost concerns for large linear and spatially complex schemes.
8. Temporary habitat impacts treated through a simplified approach –
Temporarily affected land will be handled differently from permanently lost habitat in BNG calculations.
Tip: Particularly relevant for construction compounds, access routes and phasing areas.
9. On‑site and off‑site delivery put on an equal footing for NSIPs –
Unlike the TCPA regime, NSIPs will not default to on‑site delivery where off‑site is more effective.
Tip: This creates clearer demand signals for large‑scale off‑site habitat provision.
10. Spatial risk relaxed within the NSIP BNG area –
Off‑site biodiversity units can be sourced from any LPA, NCA or (for terrestrial habitats) LNRS area overlapping the NSIP BNG boundary without penalty.
Tip: This reflects the strategic scale of infrastructure projects and their catchments.
What this signals for the off‑site BNG market
11. Larger and more stable off‑site demand from infrastructure –
NSIPs introduce long‑term, high‑volume demand into the BNG system.
Tip: Habitat providers with scalable, strategically located sites are likely to benefit most.
12. Stronger alignment with strategic nature recovery priorities –
Both TCPA and NSIP regimes are now explicitly linked to LNRS geography.
Tip: Off‑site projects that clearly support LNRS objectives are likely to remain the most attractive options.
Sources: Defra Environment Blog (20 April 2026); Government response to BNG consultations (15 April 2026); legal and professional briefings including from Gowling WLG, Burges Salmon, and Birketts.



