Five years on from Royal Assent, Defra has published its own assessment of how the Environment Act 2021 is working. The post-legislative scrutiny memorandum, published on 3 November 2026, is cautiously positive about biodiversity net gain, but far from unqualified. For anyone working in planning, development or ecology in England, it is a useful guide to how government sees BNG performing.
The memorandum comes with real numbers attached: over 10,000 hectares of habitat now on the national register, and 45 of 48 local nature recovery strategies published.
Key Takeaways
- Defra's memorandum says BNG implementation has been "broadly successful for larger developments", with over 10,000 hectares of habitat registered nationally.
- Changes affecting smaller sites came into force on 6 August 2026, including a new exemption for sites of 0.2 hectares or below.
- NSIPs became subject to the 10% BNG requirement from 2 November 2026.
- 45 of 48 local nature recovery strategies are published; the remaining three are "approaching publication".
- The review flags capacity gaps in public authorities and uncertainty over how effective conservation covenants are when land is sold or passed on.
What the Memorandum Is, and Is Not
The "Environment Act 2021: Post Legislative Scrutiny Memorandum" was prepared for the House of Commons Environment, Food and Rural Affairs Committee. It covers environmental governance, water, waste, air quality and nature, five years after the Act received Royal Assent in November 2021.
It is important to be clear about what this document is. It is Defra's own assessment of its own legislation, not an independent audit. The executive summary strikes a measured tone, stating the Act has "largely established the legal and institutional framework" intended, while acknowledging "the evidence base is not yet mature enough" to judge whether every intended outcome is being achieved. It also notes plainly: "Some delivery challenges remain, particularly around capacity, publication timelines, monitoring."
Readers should treat the findings as a government progress report, useful for understanding direction of travel, but not a substitute for independent scrutiny.
What the Review Says About Biodiversity Net Gain
The 10% BNG requirement, measured using the statutory biodiversity metric, has applied to major developments since 12 February 2024 and to minor developments since 2 April 2024. From 2 November 2026, it now also applies to nationally significant infrastructure projects (NSIPs).
On performance, the memorandum is notably upbeat about larger schemes: "The feedback and evidence government has gathered suggests BNG implementation has been broadly successful for larger developments." It reports developers increasingly seeking ecological advice earlier in the design process and adjusting site layouts to avoid biodiversity impacts rather than simply compensating for them later.
The headline figure is striking: "over 10,000 hectares of habitat created or enhanced currently listed on the national register", with further sites preparing to register. This suggests the register is becoming a genuine record of delivery, not just a compliance box.
Smaller Sites: The 2026 Changes
The picture for smaller developments is more mixed. The memorandum acknowledges that "some smaller developments and specific types of development were finding BNG a challenge." This led to a May 2025 consultation and a package of changes that came into force on 6 August 2026:
- A new exemption for sites of 0.2 hectares or below
- A new exemption for temporary development
- Repeal of the self-build and custom-build exemption
- Targeted changes to exemptions for parks, playing fields and biodiversity-related development
- Amendments to the biodiversity gain hierarchy for minor development
- Targeted changes to the metric
NSIPs Join the Regime
For nationally significant infrastructure, section 99 was commenced on 7 May 2026, and biodiversity gain statements were laid on 2 June 2026, ahead of the regime taking effect for NSIPs on 2 November 2026. Infrastructure promoters should now treat biodiversity net gain as a standard part of consenting, not an optional extra.
Local Nature Recovery Strategies: Nearly There
Forty-eight responsible authorities cover England for local nature recovery strategies (LNRSs). The first, from the West of England Combined Authority, was published on 7 November 2024. By the end of September 2026, 45 of 48 had been published, with the final three described as "approaching publication".
Government had originally estimated 12 to 18 months per strategy, but most authorities took longer. There is no legal publication deadline, and strategies must be reviewed every 3 to 10 years once in place.
Why this matters for applicants: LNRSs inform where habitat creation delivers the most value for nature recovery, and increasingly shape how local planning authorities and ecologists assess BNG proposals. Checking the relevant strategy for a site area before finalising a metric calculation is now good practice, not a formality.
Capacity Gaps in Public Authorities
The review is candid about strain within the system. Funding for local authorities totalled £46 million across 2021-22 to 2025-26, with a further £29 million committed for 2026-27 to 2028-29.
On the strengthened biodiversity duty on public authorities, in force since 1 January 2023, an initial evaluation found about one third of survey respondents were unaware of the duty or unsure whether it applied to them. Constraints identified included limited resources, ecological expertise and organisational buy-in, plus a lack of tailored guidance. Defra says it will respond to the evaluation's recommendations in due course.
For applicants, this translates into a practical risk: inconsistent capacity across planning authorities can affect timescales for validating BNG submissions and metric assurance.
Conservation Covenants and Habitat Banks
Conservation covenants, available since 30 September 2022, are growing steadily. As of 31 March 2026 there were 41 Responsible Bodies and at least 138 covenants in place, used mainly for BNG and nature recovery purposes.
The memorandum calls covenants a "respected legal tool" but is honest that their effectiveness when land is sold or passed on is not yet clear. Anyone relying on a covenant or habitat bank arrangement for off-site BNG delivery should factor this uncertainty into due diligence, particularly on long-term land transactions.
Elsewhere in the nature chapter, species conservation strategies are progressing through three pilots covering water vole, hazel dormouse and widespread reptiles. A water vole strategy has launched in East Anglia, and a reptiles strategy is in development. On protected sites, government has committed to at least 20 protected site strategies by 2029-30. Wildlife licensing reform has also reduced administrative burden, particularly for great crested newt schemes, via extended licences.
Key Figures at a Glance
| Measure | Figure |
|---|---|
| Habitat registered nationally | Over 10,000 hectares |
| LNRSs published (of 48) | 45 |
| Local authority funding, 2021-22 to 2025-26 | £46 million |
| Local authority funding, 2026-27 to 2028-29 | £29 million |
| Conservation covenant Responsible Bodies | 41 |
| Conservation covenants in place | At least 138 |
| Protected site strategies committed by 2029-30 | At least 20 |
What Developers, Landowners and Ecologists Should Do Now
- Bring ecologists in early. The memorandum itself credits early ecological advice with better outcomes on larger schemes. The earlier biodiversity is considered in site layout, the fewer costly redesigns later.
- Time baseline surveys correctly. The statutory metric depends on accurate habitat condition assessments, many of which are season-dependent. Surveys carried out at the wrong time of year can produce unreliable baselines and delay applications.
- Check exemptions carefully. The 0.2 hectare exemption, the temporary development exemption and the other 2026 changes are narrowly defined. Confirm with a qualified ecologist whether a site genuinely qualifies before assuming BNG does not apply.
- Check the relevant LNRS. With 45 of 48 strategies now published, most sites fall within an area with a published strategy that can inform habitat creation choices and strengthen planning submissions.
- Plan for the long term. BNG habitats require management and monitoring commitments, typically for extended periods. Landowners entering covenants or habitat bank agreements should understand obligations that may outlast a change of ownership.
FAQ
Is the Defra memorandum an independent review of BNG?
No. It is Defra's own assessment, prepared for parliamentary scrutiny, not an independent audit.
Does BNG now apply to all development types?
It applies to major and minor developments, and from 2 November 2026 to nationally significant infrastructure projects, subject to the exemptions set out in the 2026 amendments.
What changed for small sites in 2026?
From 6 August 2026, a new exemption applies to sites of 0.2 hectares or below, alongside a temporary development exemption and other targeted changes to exemptions and the metric.
Has every local nature recovery strategy been published?
Not yet. As of the end of September 2026, 45 of 48 had been published, with the remaining three described as approaching publication.
Are conservation covenants a reliable long-term solution?
Defra describes them as a "respected legal tool", but notes their effectiveness when land changes hands is not yet clear.
Conclusion
Defra's five-year review paints a picture of a policy framework that is largely built and, for larger developments, working reasonably well. But the same review is candid about gaps: capacity constraints in public authorities, unfinished LNRS coverage, and uncertainty over how effective conservation covenants are when land is sold or passed on. For developers, landowners and planning consultants, the practical response is the same regardless of scheme size: get ecological input early, survey accurately and at the right time of year, check exemptions and local strategies carefully, and plan management commitments for the long haul. Biodiversity Surveyors provides ecological surveys and biodiversity net gain assessments across England and can help determine how these latest changes apply to a specific site.