Skip to main content Skip to footer

Exemptions from the Biodiversity Net Gain requirement with Nina Pindham


Here is a brief summary of all the exemptions to the Biodiversity Net Gain requirements:

  • Householder applications (consultation refers to definition in Article 2 of the DMPO).
  • Permitted development under the GPDO.
  • It is indicated that Change of Use applications will be exempt. However, the consultation asks if there are any Change of Use applications that could have a significant impact on biodiversity, and which are capable of being defined. If those two criteria are met, Change of Use applications could be brought within the Biodiversity Net Gain regime.



  • The de minimis exception, that’s the threshold below which Biodiversity Net Gain requirements will apply; the initial thinking was that this would cover minor development, less than 10 units and/or 0.5 hectares. Defra has opened that up by developing a ‘small sites’ metric. This will allow sites less than 10 units or smaller than half a hectare to be able to deliver and calculate Biodiversity Net Gain at a proportionate cost, and that is subject to further consultation. Defra has moved away from looking at this from a development perspective, but they’re now applying an environmental lens to triggers for Biodiversity Net Gain. The de minimis threshold is now going to apply to the sum of all habitat types within a development site, not the scale of developments. And the de minimis threshold is also going to apply to development which impacts low and medium distinctiveness habitats only, it is not going to apply to priority habitats which are very high distinctiveness. I should clarify that when I refer to distinctiveness, and habitat and condition, I’m referring to the specific parameters that you input into the Defra metric 3.0. So very high distinctiveness habitat, in terms of the biodiversity metric, will not be subject to the de minimus exception.
  • Reserve Matters Consent. Where outline permission is not subject to Biodiversity Net Gain requirements, I don’t see that falling within the regime. It’s not specifically covered in the consultation. It does refer to phased development and subsequent consents, but of course those are wider categories than just Reserved Matters Consent. In practical terms, I don’t see how you can possibly calculate what a 10% uplift would be, where the baseline Biodiversity Net Gain value was not measured.
  • Section 73 and section 73A applications under the Town and Country Planning Act will be within the regime, so a section 73 application will still be subject to the same Biodiversity Net Gain requirement as the original planning permission, and any section 73 application that will affect any post development biodiversity value will require an entirely new biodiversity gain plan, applying the baseline of the outline original permission.
  • Irreplaceable habitat will be exempt. It’s not captured by the metric so it can’t be done. Bespoke plans are envisaged there, and the government is going to set a definition of that in the secondary legislation, so we’ll have more clarity on that.
  • The exemption for Brownfield development is interesting. In practice, an exemption for Brownfield development will apply when the baseline biodiversity score is zero because 10% of 0 is still 0, but where there is habitat, it will be caught by the Biodiversity Net Gain requirement.
  • Defra is also considering making projects that enhance biodiversity for the purposes of discharging the net gain requirement exempt and also, they’re considering self-build custom house building. At the moment though, the government doesn't see a clear need for the latter being exempt so it looks like it will be within the regime.


56 things planners need to know about BNG

After collaborating with The Planner to showcase a webinar for Local Planning Authorities on how to make BNG work in your area, we have compiled 56 questions and answers that we received from the webinar to equip you with all the info you need. 

About the author

Environment Bank