Two words buried in a technical amendment can decide whether a housebuilder owes thousands of pounds in biodiversity credits or nothing at all. That is exactly what happened on 21 October 2026, when the Joint Committee on Statutory Instruments met to scrutinise one of this year's most consequential planning instruments. Its Twelfth Report, published on 23 October 2026, flagged the biodiversity net gain section 73 transitional rules JCSI October 2026 inquiry as requiring "elucidation", committee-speak for "this needs a better explanation." The regulations survived unscathed, but the clarification changes how practitioners should read the rules.
This matters because the underlying instrument, SI 2026/790, reshaped who qualifies for biodiversity net gain exemptions across England. Developers relying on a loose reading of the transitional provisions risk miscalculating liability on section 73 variation applications, an error that could cost real money or delay a scheme.
Key Takeaways
- The JCSI did not strike down, suspend, or amend SI 2026/790; the August 2026 exemptions remain fully in force.
- The committee questioned why regulations 7A(5), 7B(6) and 4 use two separate date tests rather than one.
- Defra's explanation: an original permission can exist without an application (for example, under the GPDO), so both limbs are needed.
- The practical rule is strict: a section 73 permission only gets the new exemptions if BOTH the original application AND the original permission date from on or after 6 August 2026.
- Developers and ecologists must now record four data points before assessing any section 73 case: application date, permission date, consent route, and any predecessor exemption used.
What the Committee Actually Found
The JCSI's job is not to judge policy merit. It checks that statutory instruments are drafted clearly, lawfully, and within the powers Parliament granted. Its Twelfth Report, covering the meeting on 21 October 2026, drew SI 2026/790 to the attention of both Houses purely on clarity grounds.
The regulations in question, the Biodiversity Gain (Town and Country Planning) (Amendments and Transitional Provisions) (England) Regulations 2026, were made in July 2026 and came into force on 6 August 2026. They introduced several new exemptions and a revised biodiversity gain hierarchy. The committee's concern centred on the transitional provisions governing section 73 permissions: permissions that vary conditions on an existing consent.
Inserted regulations 7A(5) and 7B(6), along with regulation 4, each disqualify a section 73 permission from the new exemptions if either the original application or the original permission predates 6 August 2026. The JCSI asked, in effect: why two tests instead of one? Wouldn't a single date, say, the original application date, be simpler?
Defra's Answer, and Why It Matters
Defra's response, recorded in the report's appendix, resolved the puzzle. Not every permission has a corresponding "application" in the conventional sense. A permission granted under the General Permitted Development Order 2015 (GPDO) arises automatically from permitted development rights, without a traditional planning application. If the rules only tested the application date, GPDO-derived permissions would have no clear anchor point.
So the drafting uses two alternative tests to catch every route to consent: application date where one exists, permission (grant) date where it does not. Both limbs must point to on-or-after 6 August 2026 for the new exemptions to apply to a section 73 permission.
"An original permission can exist without an application, the grant-date limb exists precisely to cover that gap."
This is the central interpretive point to take from the biodiversity net gain section 73 transitional rules JCSI October 2026 clarification: the two dates are not duplicative, they are complementary safety nets.
The Strict Rule Developers Must Apply
Cutting through the drafting technicality, the operative rule is simple to state but easy to misapply:
A section 73 permission can only benefit from the new August 2026 exemptions if BOTH the original application and the original permission are dated on or after 6 August 2026. If either date predates 6 August 2026, the new exemptions do not apply.
This is a conjunctive test, not a disjunctive one. Both conditions must be satisfied. Missing either one disqualifies the scheme from the new exemptions regardless of when the section 73 application itself is submitted.
Worked Examples
| Scenario | Application Date | Permission Date | Section 73 Submitted | Outcome |
|---|---|---|---|---|
| Fresh small site | After 6 Aug 2026 | After 6 Aug 2026 | N/A | May qualify for small-site exemption |
| Variation on older consent | Before 6 Aug 2026 | Before 6 Aug 2026 | After 6 Aug 2026 | Does NOT gain small-site exemption |
| GPDO-derived consent | No application exists | After 6 Aug 2026 | After 6 Aug 2026 | Grant-date limb applies; may qualify |
The second example is the one that trips people up. Submitting a section 73 application after the commencement date does not retrospectively modernise a permission rooted in a pre-August application. The clock started ticking at the original application, not the variation.
What SI 2026/790 Actually Changes
Separate from the committee's drafting query, the substantive content of the regulations remains important context:
- Small-site exemption: Sites up to 0.2 hectares with no onsite priority habitat affected are exempt from BNG requirements. Government estimates this removes roughly 50% of residential permissions from BNG obligations and cuts demand for off-site units by about 10%.
- Temporary development exemption: Permissions lasting up to five years are exempt, but this exemption cannot be stacked with extensions or successive grants.
- Self-build/custom-build exemption: Removed for applications made on or after 6 August 2026, but preserved for earlier applications and for later section 73 permissions where the original consent already used the exemption.
- Revised biodiversity gain hierarchy (article 37A DMPO): For non-major development, applicants may now pursue onsite enhancement or registered offsite units before falling back on statutory biodiversity credits.
Separately, mandatory BNG for Nationally Significant Infrastructure Projects takes effect for DCO applications made on or after 2 November 2026, requiring a 10% net gain with 30 years of maintenance, a distinct but related compliance milestone worth noting alongside the section 73 transitional provisions.
Practical Steps for Developers and Ecologists
Given the biodiversity net gain section 73 transitional rules JCSI October 2026 findings, practitioners should treat due diligence as non-negotiable:
- Record the original application date, not the section 73 submission date.
- Record the original permission (grant) date, especially for GPDO or deemed consents.
- Identify the consent route, standard application, GPDO, or another permitted development mechanism.
- Check for predecessor exemptions, such as prior self-build/custom-build reliance, which may carry forward.
- Commission a baseline habitat survey early, before assuming any exemption applies.
- Consult an ecologist on whether the small-site exemption, temporary development exemption, or the revised hierarchy is the correct pathway.
Firms such as Biodiversity Surveyors, which provide ecological surveys and BNG assessments across the UK, can help establish these baseline facts before a section 73 application is drafted, reducing the risk of a costly recalculation later in the process.
Frequently Asked Questions
Did the JCSI block or change SI 2026/790?
No. The committee flagged the instrument for requiring elucidation. It did not strike it down, amend it, or suspend it. The August 2026 exemptions remain fully in force.
What is the key rule for section 73 permissions under the new exemptions?
A section 73 permission can only benefit from the new August 2026 exemptions if both the original application and the original permission are dated on or after 6 August 2026. If either date predates 6 August 2026, the new exemptions do not apply.
Why are there two different date tests in the regulations?
Because some permissions, such as those granted under the GPDO, exist without a corresponding application. The grant-date limb covers those cases; the application-date limb covers conventional applications.
Does submitting a section 73 application after 6 August 2026 help an older scheme qualify?
No. If the original application or original permission predates 6 August 2026, submitting the section 73 variation later does not unlock the new exemptions.
What size threshold applies to the small-site exemption?
Sites up to 0.2 hectares qualify, provided no onsite priority habitat is affected.
When does mandatory BNG apply to Nationally Significant Infrastructure Projects?
For DCO applications made on or after 2 November 2026, requiring a 10% biodiversity net gain maintained for 30 years.
Conclusion
The JCSI's Twelfth Report does not change the law, but it sharpens how everyone should read it. The biodiversity net gain section 73 transitional rules JCSI October 2026 clarification confirms that Defra's dual date test was a deliberate design choice, not drafting sloppiness, and it reinforces a strict conjunctive rule that many practitioners may have been applying too loosely. Developers and ecologists handling section 73 applications should immediately audit live and pipeline schemes against both date limbs, commission early baseline surveys, and seek ecological advice before assuming an exemption applies. Getting this wrong is not a technicality; it is a direct cost and delay risk.