My Site Is Under 0.2 Hectares. Do I Still Need Biodiversity Net Gain?
My Site Is Under 0.2 Hectares. Do I Still Need Biodiversity Net Gain?
The rules surrounding Biodiversity Net Gain (BNG) changed in August 2026, including a significant new exemption for some smaller development sites.
This raises an obvious question for applicants and developers:
If my site is 0.2 hectares or smaller, do I still need to deliver 10% Biodiversity Net Gain?
For some developments, the answer is now no, but there are important exceptions.
What changed in August 2026?
For planning applications submitted in England on or after 6 August 2026, development on a site measuring 0.2 hectares or less is exempt from mandatory BNG, provided that the development does not impact an onsite priority habitat.
The site area is based on the land within the planning application's red-line boundary.
This represents a significant change for smaller developments which would previously have fallen within the statutory BNG regime.
However, the exemption should not automatically be interpreted as meaning that ecology no longer needs to be considered.
What if there is priority habitat on the site?
This is an important qualification.
The 0.2 hectare exemption does not apply where the development impacts onsite priority habitat. The same restriction applies to the existing de minimis exemption and the new temporary-development exemption.
Whether a habitat is present, what condition it is in and whether the proposals will impact it therefore remain important considerations when determining whether an exemption genuinely applies.
Is this the same as the de minimis exemption?
No.
The de minimis exemption continues to exist separately.
Broadly, this can apply where a development does not impact priority habitat and affects less than 25 m² of onsite habitat and less than 5 m of linear habitat, such as hedgerow.
The newer exemption is different because it relates to the overall area of the development site, rather than simply the amount of habitat affected.
What about self-build developments?
This is another area where the rules have changed.
The previous exemption specifically for self-build and custom-build development no longer applies to new planning applications made on or after 6 August 2026. Transitional arrangements mean that qualifying applications made before that date can remain exempt.
However, a new self-build proposal could potentially qualify for the 0.2-hectare exemption instead, provided it meets the relevant criteria.
Does being exempt from BNG mean ecology doesn't matter?
No.
BNG and ecological impact assessment are not the same thing.
A development being exempt from the statutory BNG requirement does not remove other ecological considerations.
For example, a site may still contain or provide habitat for protected species, important habitats, nesting birds, trees or hedgerows. Local planning policy may also require biodiversity conservation or enhancement independently of the statutory 10% BNG requirement.
This distinction is particularly important on small sites.
A relatively small area can still contain ecologically valuable features.
Should ecology be considered before fixing the red-line boundary?
Yes.
The red-line boundary should reflect the development being applied for and should not simply be manipulated to avoid BNG. However, understanding the ecological implications of the proposed development boundary early in the design process can prevent problems later.
Early ecological input can help establish:
whether the statutory BNG requirement is likely to apply;
whether priority habitat could prevent an exemption being used;
what other ecological surveys or assessments may be necessary; and
whether opportunities exist to retain and enhance biodiversity even where mandatory BNG does not apply.
Exempt doesn't have to mean no biodiversity gain
One of the positive aspects of smaller developments is that relatively straightforward measures can sometimes make a meaningful difference.
Retaining existing trees and hedgerows, incorporating native and nectar-rich planting, creating small areas of species-rich habitat, providing integrated bird or bat features, maintaining connectivity through gardens and designing drainage features with biodiversity in mind can all contribute.
These measures may not constitute statutory BNG, but they can still make a development better for wildlife.
The key message
For planning applications submitted on or after 6 August 2026, development sites of 0.2 hectares or less may now be exempt from mandatory Biodiversity Net Gain.
But the exemption isn't simply:
“Under 0.2 hectares = no ecology required.”
Priority habitat can prevent the exemption applying, and BNG is only one part of the ecological planning process.
Understanding the habitats present and considering ecology early remains the best way to establish what a development actually requires, and to identify opportunities to create a better outcome for nature at the same time.
At nichecology®, we support developers, homeowners and planning teams with ecological assessment and Biodiversity Net Gain from the early design stages through to planning and delivery.
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