Biodiversity Net Gain: What Is It, What Is Changing in 2026 and What Does It Mean for You?
Biodiversity Net Gain (BNG) has fast become one of the most significant environmental requirements affecting development in England. It is an approach to improving biodiversity by requiring developments to leave the natural environment in a measurably better state than before development took place.
In 2024, BNG became mandatory and since, the rules have had major impacts on developers, landowners, environmental consultants and local authorities. Many people support BNG and see it as a crucial step towards supporting long-term nature recovery and reversing biodiversity loss. The benefits of the BNG regime is already becoming clear and it is set to prevent 6,000-10,000 hectares of habitat loss annually. However, others argue that BNG can be complex, costly and difficult to deliver, particularly for smaller developments and SMEs (small & medium-sized enterprises).
This year, England's BNG regime will be undergoing it's biggest revision since becoming mandatory 2 years ago. The government are introducing a series of significant changes aimed at simplifying the regime, supporting housing delivery and reducing burdens on SMEs and Local Authorities.
In this article, WSCA have helped break down what BNG is, what the key changes expected in 2026 are, and what they can mean for you.
What is Biodiversity Net Gain?
BNG is a way of creating and improving biodiversity; this happens by requiring a development to have a positive impact on biodiversity. In England, BNG is required under statutory framework and, depending on some exceptions, every planning permission is deemed to have been granted subject to the condition that the BNG objective is met.
This objective is that a development must deliver at least a 10% increase in biodiversity value, relative to the pre-development value of the onsite habitat. This can be achieved through onsite biodiversity gains, registered offsite biodiversity gains, or statutory biodiversity credits.
The statutory framework for BNG is imposed as a post-permission matter to ensure that the objective above will be met for any development granted planning consent; this is through a pre-commencement condition on the consent of the development. Once planning permission has been granted, unless exempt (which we cover below), a Biodiversity Gain Plan must be submitted and approved by the Local Authority prior to the commencement of the development. It is, however, important that BNG is considered throughout the planning process to ensure the objective is met and can be fully discharged successfully.
In some circumstances, developments may be exempt from BNG; some examples of when this may currently apply include:
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Householder applications - this includes home extensions, conservatories, loft conversions, and other domestic alterations
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'De minimus' developments - where a proposal affects less than 25sqm of non-priority habitat
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Self-build schemes - must meet specific criteria, including no more than 9 dwellings on a site smaller than 0.5ha
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Certain variations to existing planning permissions - for example, Section 73 or Section 96A applications
What Are The Changes to Biodiversity Net Gain in 2026?
Changes to BNG are expected to be introduced by the end of July 2026. This consists of some further exemptions, as well as other changes, including:
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Introduction of new 0.2hectare area-based exemption - any developments on sites of 0.2ha or smaller will be exempt from the mandatory BNG requirements, provided they do not affect priority habitat. t is estimated by the government that this could remove BNG obligations from around 50% of residential planning permissions that are currently affected by the regime.
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Removal of the existing exemption for small scale self-build and custom-build developments - this is mainly due to the fact that more qualifying schemes would fall into the new 0.2ha threshold instead.
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Exemption of temporary developments - any temporary planning permissions lasting up to 5 years are expected to become exempt from mandatory BNG requirements.
Later in 2026, the government expect to:
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Introduce an exemption for development that aims to enhance parks, playing fields or public gardens, where no priority habitat is affected
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Introduce an exemption for development where the primary objective is to enhance or conserve biodiversity
All of these changes, in particular the changes proposed at the end of July, are aiming to make BNG simpler and more practical for smaller developers, in order to recognise their vital role in delivering housing and local growth. They aim to reduce administrative burdens and provide greater flexibility for minor developments while still supporting the continued growth of the BNG market.
What Could This Mean for You?
Whether you are a small developer or a developer for larger residential and commercial schemes, this change will most likely have an impact on you.
For smaller developments, the change is likely to have a positive impact as it is largely aimed at helping small housebuilders and SMEs. Currently, even relatively small projects (for example, the erection of 1 dwelling) often require biodiversity calculations, ecological surveys, habitat plans and long-term management agreements. However, the new regime therefore seeks to help reduce planning costs for smaller developers, as well as speed up planning applications and simplify biodiversity assessments, in order to encourage housing delivery on smaller sites. The government are also aiming to make it easier for small developments to rely on off-site biodiversity gains, rather than depending on habitat improvements directly on the site itself.
On the other hand, larger developments are most likely going to face more extensive BNG obligations; it will become more embedded and strategic. Large developers are likely to face:
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Long-term habitat management obligations
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Continued biodiversity assessment requirements
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Greater reliance and flexibility in sourcing off-site biodiversity units
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Increased scrutiny around environmental delivery
Major schemes above the new exemption threshold will still be required to achieve at least a 10% biodiversity gain; however, the new regime will increasingly push larger developers towards more strategic, landscape-scale biodiversity delivery, as opposed to small on-site habitat interventions.
The key change for large developers is the potential for greater flexibility in sourcing off-site biodiversity units. The proposed changes intend to make off-site delivery easier and more practical where on-site provision is difficult.
At the same time, in November 2026, BNG will become compulsory for Nationally Significant Infrastructure Projects (NSIPs); this includes major transport, utility and energy schemes. Infrastructure providers and large developers are likely to become the primary drivers of demand for biodiversity units in the future, due to the projects often affecting substantial areas of land; therefore, these large developments may require large-scale habitat creation over wide demographic areas.
To summarise, the 2026 BNG reforms represent a significant shift in the direction of Biodiversity Net Gain policy in England. While the core principle of improving biodiversity through development remains the same, the upcoming proposed changes demonstrate a clear aim towards reducing the burden on SMEs and smaller developments, while simultaneously placing greater emphasis on larger schemes.
The changes aim to balance housing delivery with environmental protection; as the reforms are introduced, BNG will remain an important part of the planning process and the future of environmental development in England.
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