Biodiversity Net Gain Changes 2026: What Developers Need to Know

Updated August 10th, 2026

Over the past few years, Biodiversity Net Gain (BNG) has become part of everyday planning. The latest changes introduce some genuinely practical exemptions, and overall are a positive step. These updates are not about weakening BNG, they’re about making it more proportionate.

The new 0.2 hectare exemption – (approximately 4-8 homes).

One of the most useful changes is the new exemption for sites at or under 0.2 hectares, provided they aren’t affecting a Priority Habitat. In practical terms, that’s often the sort of site that might deliver somewhere in the region of four to eight homes, depending on the layout and access. It’s not a huge area, but it should reduce the amount of genuinely unnecessary work on small developments where the environmental gains were often limited, while still allowing BNG to focus on sites where it can have the greatest impact. This should reduce the frustration in the industry and help BNG be viewed in a better light.

Priority Habitat – the important catch.

The exemption isn’t automatic. If your proposal involves impacting a Priority Habitat, then BNG still applies. The most common examples I come across on development sites are native hedgerows and woodland, although priority habitat ponds and some grasslands can also be relevant. A good example is site access. If your site is at or under the 0.2-hectare threshold but you need to remove part of a native hedgerow to create access, you’ve immediately changed the picture. That’s why it’s worth checking habitats early, before designs become fixed.

Temporary planning permissions (five years or less)

The other amendment I’m genuinely relieved about is the new exemption for temporary planning permissions of five years or less. I’ve been asked to carry out BNG assessments for temporary school classrooms, event spaces and other short-term developments that were always going to be removed and the land put back as it was. It never really felt like that was the purpose of Biodiversity Net Gain.

One example of this is a music festival held in the same park every year. If every temporary event had to keep delivering biodiversity gains, eventually you’d end up slowly turning the park into a forest. That was always an odd consequence of how the rules worked in practice, rather than what BNG was actually trying to achieve. This exemption feels much more proportionate.

The exemptions that were already there – De Minimis Exemption.

It’s also worth remembering that some exemptions haven’t changed. The de minimis exemption still applies where habitat loss is less than 25 square metres, or less than five metres of hedgerow is removed. That’s particularly useful for hardstanding sites, small amendments to planning permissions and other developments where there really isn’t a meaningful ecological impact.

The self-build exemption has been removed.

Many self-build projects will now fall within the new 0.2-hectare exemption anyway, so in practice this change is more likely to affect larger self-build sites. The previous exemption probably had merit, but understandably the government has tried to simplify the system.

The evolution of BNG.

BNG has evolved over a long period. The early pilots started back in 2012, and although the legislation is now established, we’re still refining it. These latest changes are another example of that evolution. Expect more adjustments in the future. The important thing is that we continue improving the system rather than abandoning it altogether. Despite the frustrations that all new planning policy brings, Biodiversity Net Gain is a genuinely positive step for nature and can lead to better development overall.