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More than 10,000 hectares of created or enhanced habitat now sit on England's national biodiversity gain register. That figure comes from a new Defra review of the Environment Act 2021, published on 3 November 2026 [1]. In the same week, mandatory biodiversity net gain (BNG) started to apply to the largest infrastructure schemes in the country [2]. For anyone following biodiversity net gain November 2026 developments, these two events set the tone for the months ahead: the rules are broadly working for large sites, but smaller schemes and public bodies still struggle, and the net is now widening to nationally significant projects.
Key Takeaways
- Defra published a post-legislative scrutiny memorandum on the Environment Act 2021 on 3 November 2026, five years after Royal Assent [1].
- Defra describes mandatory BNG as "broadly successful for larger developments", with developers seeking ecological advice earlier [1].
- Over 10,000 hectares of habitat are listed on the national biodiversity gain register, though listing alone does not prove ecological targets have been met [1].
- Mandatory BNG applies to qualifying Nationally Significant Infrastructure Project (NSIP) applications made on or after 2 November 2026 [1][2].
- The 0.2 hectare small-sites exemption and related amendments took effect on 6 August 2026 [2].
What Defra's Environment Act Review Says
Defra prepared the memorandum for the Environment, Food and Rural Affairs Committee, as part of standard post-legislative scrutiny [1]. The review covers the whole Act, but the BNG and Local Nature Recovery Strategy (LNRS) measures mainly apply in England.
The headline message is cautious. The executive summary states that "the evidence base is not yet mature enough" to show whether some intended environmental outcomes are being achieved [1]. In other words, the system is running, but it is too early to say how much nature it has actually delivered.
On BNG specifically, Defra is more positive. It describes mandatory BNG as "broadly successful for larger developments" [1]. Developers are getting ecological advice earlier in the design process and are thinking about habitat retention and creation sooner than they did before the rules came in.
"Broadly successful for larger developments" is Defra's verdict on mandatory BNG so far, according to the 3 November 2026 memorandum [1].
The biodiversity gain register in numbers
The review reports that more than 10,000 hectares of created or enhanced habitat are listed on the national biodiversity gain register, with further projects being prepared for registration [1]. There is an important caveat. A register entry shows that a site has been secured and recorded. It does not mean the habitat has finished its maintenance period or hit its ecological targets. Monitoring over the 30-year management period is what proves the gain.
Biodiversity Net Gain November 2026: Where Small Sites Stand
The review is frank that smaller developments and some site types have struggled with compliance [1]. That matches what many ecologists and small builders have reported since BNG became mandatory for small sites in April 2024 [2].
In response, the government made a package of changes during 2026. According to the NFU's summary of the amendments, the following took effect on 6 August 2026 [2]:
The review also refers to a revised biodiversity gain hierarchy introduced in 2026 [1]. Developers of small and medium schemes should check which version of the rules applied on the date their application was submitted, because the exemption thresholds changed mid-year.
Mandatory BNG for Nationally Significant Infrastructure Projects
The second major development is separate from the review but landed in the same week. Under separate legislation, mandatory BNG now applies to qualifying Development Consent Order applications for Nationally Significant Infrastructure Projects made on or after 2 November 2026 [1][2].
The NFU notes that NSIP applicants can deliver gains on-site or off-site first, and may buy statutory biodiversity credits only as a last resort [2]. This mirrors the hierarchy that applies to Town and Country Planning Act schemes. For promoters of large energy, transport and water projects, the practical effect is that ecological baseline work and habitat strategy must now be built into the pre-application stage rather than bolted on later.
Local Nature Recovery Strategies and the Public Authority Duty
Two further findings from the review matter for landowners and councils.
First, 45 of England's 48 Local Nature Recovery Strategies had been published by the end of September 2026 [1]. Most took longer than Defra's original expectation of 12 to 18 months. This is a September snapshot, not a current count, but it shows the mapping layer that underpins off-site BNG is now largely in place.
Second, Defra ran an initial evaluation of the strengthened biodiversity duty on public authorities. About one third of survey respondents were unaware of the duty or unsure whether it applied to them [1]. Defra identifies shortfalls in resources, ecological expertise, guidance and organisational support. As the Planning Geek report cautions, this is a survey figure and should not be read as the share of all councils [1].
What the Review Does Not Do
It is worth being clear about the limits of the memorandum. The review does not amend planning law and does not create any new exemptions [1]. It is an evidence document for Parliament. Any future changes to the BNG regime would need separate regulations or guidance.
Equally, register entries, published strategies and approved planning conditions do not by themselves prove that biodiversity gains have been achieved [1]. Delivery is proven on the ground, through monitoring reports over the management period.
What This Means for Developers and Landowners
For developers of major schemes, the message is that early ecological input pays off. Defra's own review credits earlier advice and earlier habitat thinking for the success of BNG on larger sites [1]. A UK Habitat Classification (UKHab) baseline survey, carried out in the right season, and an accurate statutory metric calculation are the foundations of a credible biodiversity gain plan.
For NSIP promoters, the 2 November 2026 start date means baseline survey programmes, habitat strategies and any off-site unit procurement should be mapped against the Development Consent Order timetable now [2].
For small builders, the 0.2 hectare threshold and the off-site route for minor development can simplify compliance, but the removal of the self-build exemption catches some projects that were previously outside the regime [2]. A short pre-application ecological review will confirm which rules apply.
For landowners, the growth of the register to over 10,000 hectares shows there is real demand for habitat units, each secured for at least 30 years [1][2]. A feasibility assessment can show whether a parcel is suitable for a habitat bank and what baseline, legal agreement and monitoring would be needed.
An experienced ecological consultant can carry out the baseline survey, run the metric, advise on the gain hierarchy, prepare the biodiversity gain plan and set up the long-term monitoring that turns a register entry into a proven gain.
FAQ
When did mandatory BNG start applying to NSIPs?
Mandatory BNG applies to qualifying NSIP Development Consent Order applications made on or after 2 November 2026 [1][2].
What is the small-sites exemption threshold?
Developments below 0.2 hectares are exempt from mandatory BNG. This exemption took effect on 6 August 2026 [2].
Does Defra's review change the BNG rules?
No. The memorandum published on 3 November 2026 is a post-legislative scrutiny document. It does not amend planning law or create new exemptions [1].
How much habitat is on the national biodiversity gain register?
Defra reports more than 10,000 hectares of created or enhanced habitat on the register, with more projects in preparation. Listing does not by itself prove ecological targets have been met [1].
Conclusion
The biodiversity net gain November 2026 picture is one of a maturing system. Defra's Environment Act review finds BNG working well for larger developments, while admitting the evidence base is still thin and smaller sites have struggled [1]. The 2026 amendments, including the 0.2 hectare exemption, aim to fix the small-site problem [2]. At the same time, the regime has expanded to cover Nationally Significant Infrastructure Projects from 2 November 2026 [1][2].
Next steps for anyone with a scheme in the pipeline: check which exemptions apply on your application date, commission a seasonally appropriate baseline survey early, and plan the 30-year monitoring from the outset. Landowners with suitable land should consider a habitat bank feasibility study while demand for units continues to grow.
References
- Environment Act Review. planninggeek.co.uk.
- Biodiversity Net Gain Consultation Latest News. nfuonline.com.