England Biodiversity Net Gain Rules Change on 6 August 2026

Planning law can look forbidding on the page, but this change is easier to follow once you strip out the cross-references. England’s new Biodiversity Gain regulations come into force on 6 August 2026 and do three practical things: they relax the biodiversity gain hierarchy for non-major development, create two new exemptions, and remove the old self-build and custom-build exemption. (legislationtracker.co.uk) **What this means:** if you are submitting a planning application on or after 6 August 2026, the date is not a footnote. It decides whether you fall under the new rules or the old ones. (legislationtracker.co.uk)

Before we get to the legal edits, it helps to reset the basics. Defra’s guidance says biodiversity net gain, usually shortened to BNG, is the rule that development should leave habitats for wildlife in a measurably better state than before. In England, most permissions in scope must achieve at least a 10% gain, and the biodiversity gain condition usually means a Biodiversity Gain Plan has to be approved before development begins. (gov.uk) In everyday English, that means a builder cannot simply damage habitat and move on. The system expects the loss to be avoided or reduced first, then made up through habitat work on-site, through registered off-site gains, or, if those routes are not possible, through statutory biodiversity credits. Defra and Natural England say off-site gains must be recorded on the biodiversity site register, while statutory credits remain the last-resort option. (gov.uk)

The first rule change is about the **biodiversity gain hierarchy**, which is planning shorthand for the order in which developers are expected to solve the biodiversity problem. Defra’s April 2026 response said the government would change the hierarchy for minor development only, meaning development that is not classed as major. The new regulations do that by putting three options on the same rung for non-major schemes: enhancing habitat on the site, creating habitat on the site, or using registered off-site biodiversity gains. (gov.uk) That is a real shift. For smaller schemes on cramped plots, off-site gains are no longer treated as clearly lower preference than on-site creation or enhancement. But the last step stays the same: statutory biodiversity credits are still supposed to be used only when those other routes cannot be done. (legislationtracker.co.uk)

The second change is the new **0.2 hectare exemption**. From 6 August 2026, development on a site no larger than 0.2 hectares can be exempt from the biodiversity gain planning condition, but only if it does **not** impact an on-site priority habitat. Defra’s wider guidance explains that priority habitats are habitats on the Secretary of State’s list under section 41 of the Natural Environment and Rural Communities Act 2006, so this is not a blanket pass for every tiny plot. (legislationtracker.co.uk) Defra’s evidence annex explains why ministers chose this route. The department says the smallest sites can face fairly heavy process costs, especially where ecological input is needed, and it estimates that a 0.2 hectare exemption could save developers about £17.4 million a year. The same annex also says this threshold could exempt about 51% of BNG-eligible planning applications and leave around 12% of biodiversity units uncompensated compared with the current position, which is why the argument over proportionality versus nature loss is not going away. (assets.publishing.service.gov.uk)

The third change is aimed at **temporary development**. If the whole scheme is temporary, the permission lasts no more than five years, and there is no impact on an on-site priority habitat, the biodiversity gain planning condition does not apply. The regulations also stop applicants from stretching that exemption through repeat permissions: if the total permitted period for the same temporary development goes past five years, the carve-out falls away. (legislationtracker.co.uk) For you as a reader, the big point is that ‘temporary’ does not mean ‘light-touch’ by default. The permission has to be genuinely temporary in planning terms, with an end point and reinstatement built into the condition. If the site includes priority habitat, or the time limit grows beyond five years, the exemption is not there. (legislationtracker.co.uk)

The rule many people may miss is the one that disappears. The regulations remove the earlier exemption for certain self-build and custom-build development, and Defra had flagged that change in its April 2026 policy update. So if you are a self-builder looking at a fresh application after 6 August 2026, you should not assume the old carve-out still protects you. (defraenvironment.blog.gov.uk) There is, though, a transition safeguard. Applications made before 6 August 2026 can continue under the older arrangements in some cases, and that includes some later section 73 permissions linked to earlier approvals. Defra’s planning guidance explains section 73 as the route used to vary or remove a planning condition on an existing permission, which matters here because BNG rules can follow the history of the original permission, not just the date on the newest paperwork. (legislationtracker.co.uk)

So who is most affected? First, small developers and SME housebuilders, because the 0.2 hectare exemption is designed to cut costs on the smallest sites. Defra’s evidence annex says smaller developers can be hit harder by planning costs, and it also points to a 2025 local authority survey where ecology and biodiversity came out as the top planning skill gap, reported by more than half of planning departments. Councils, applicants and advisers will all feel that administrative change. (assets.publishing.service.gov.uk) Second, landowners and habitat providers in the off-site market are watching closely. Defra’s evidence suggests a 0.2 hectare exemption could mean around 42% fewer off-site trades and about 10% lower market value than the no-exemption position. And during consultation, many respondents warned that even small-site exemptions can add up to noticeable cumulative biodiversity loss, especially in towns where small plots still matter for habitat links and everyday green space. (assets.publishing.service.gov.uk)

If you are trying to work out whether this law changes your next application, four questions get you most of the way there. Was the application made before or after 6 August 2026? Is the site 0.2 hectares or smaller? Does the scheme affect an on-site priority habitat? Is the permission temporary, and if so does the total period stay within five years? If the answer to that last question is no, or if priority habitat is involved, the new exemptions may not help. (legislationtracker.co.uk) The bigger lesson is that this is not just a tidy-up of wording. Defra is trying to make BNG simpler for small and short-lived schemes while keeping the main 10% rule in place. Whether that looks like sensible proportion or a retreat from local nature recovery will depend on where you sit. Either way, from 6 August 2026 the small-print around England’s planning applications changes, and anyone using old self-build assumptions needs to update their reading now. (gov.uk)