Construction of a large multi-storey building on a hill in Lynmouth, Devon in April 2022.
On 16 April the UK government published its response to a consultation on improving the implementation of Biodiversity Net Gain (BNG) across minor, medium and brownfield development, outlining a package of reforms intended to streamline delivery while maintaining environmental outcomes.
The announcement from Defra confirms a series of regulatory changes to be introduced through secondary legislation in 2026. These include: the removal of the self-build and custom build exemption, the introduction of a 0.2 hectare exemption for small sites, and updates to how BNG applies to Nationally Significant Infrastructure Projects (NSIPs).
Industry bodies and environmental groups have broadly welcomed elements of the reforms, but significant concerns remain about policy clarity, environmental ambition, and the potential impact on nature recovery.
Industry welcomes clarity but flags ongoing uncertainty
The Environmental Industries Commission (EIC) described the Government’s response as a positive step toward providing greater certainty for developers and environmental service providers. Clearer timelines and updated guidance were pinpointed for praise, alongside a new consultation focused on brownfield residential development.
Marie-Claude Hemming, Policy Director at EIC, said:
“These announcements send a strong and welcome signal that Government is listening and acting on industry feedback.
Getting Biodiversity Net Gain right is critical, and this added clarity on exemptions, timescales and nationally significant infrastructure project (NSIP) implementation gives EIC members the certainty they need to plan and invest with confidence. Crucially, it keeps the focus where it belongs: on delivering tangible, lasting gains for nature.”
The confirmed changes include exemptions for temporary permissions of up to five years and amendments to the biodiversity gain hierarchy for minor development – measures intended to reduce administrative burdens while maintaining core BNG principles.
Concerns over delays, thresholds and market confidence
However, some in the sector argue that the reforms do not go far enough in addressing uncertainty.
Robert Oates, CEO of Arbtech, one of the UK’s leading ecological consultancies, said:
“The Government has seen sense in scrapping the self-build and custom build exemptions — these loopholes were being widely misused and risked undermining the integrity of the BNG market. That’s a welcome step forward. The introduction of a clear 0.2 hectare exemption should also help reduce friction for smaller sites.
“But beyond that, the picture remains far too uncertain. Piecemeal announcements, a lack of clear timelines, and ongoing questions around the future of the de minimis threshold are creating instability at a point when the market needs confidence. Consulting on potential changes is welcome – but we already know the current de minimis thresholds are being misused, and action is needed sooner rather than later.
“This uncertainty has real-world consequences – developers delay, investors hesitate, and projects stall. That ultimately slows both housebuilding and nature recovery.
“If the Government wants BNG to deliver, it needs to move quickly from consultation to clarity, and provide a stable, fully defined framework the market can rely on.”
Similar concerns were echoed by the BNG Federation, particularly regarding the treatment of smaller sites and the sequencing of consultations and impact assessments.
Claire Traynor, a representative of the BNG Federation and Chief Commercial Officer at Nattergal, said:
“The Government’s guidance on biodiversity net gain for NSIPs is sensible policy — it keeps BNG firmly in the framework for major infrastructure while removing a disproportionate burden that was never justified. That’s the right balance.
“The small sites picture is another story with more deferrals and unclear timelines. The Government confirmed an exemption this week, whilst leaving others for later consideration, and won’t publish an impact assessment regarding small sites until after the next consultation has already started. That is not a stable framework, and the outcome will be further confusion and delays to development, uncertainty for investors and slowed progress on vital nature restoration.
“The government cannot build faster while simultaneously giving developers reasons to wait.”
Environmental groups warn of weakening protections
Environmental stakeholders have also raised concerns that some of the changes could dilute the effectiveness of BNG as a nature recovery tool.
In a statement following Defra’s announcement, The Rivers Trust said that while some “clear steps forward have been made to unblock biodiversity-boosting projects,” the Government has “persisted with the overall weakening of this nature-positive policy.”
The organisation welcomed the planned exemption for habitat creation projects, describing it as essential for accelerating nature recovery and delivering environmental targets. However, it warned that the new 0.2 hectare exemption for development sites could significantly reduce funding for biodiversity enhancements.
According to The Rivers Trust, government evidence indicates that the exemption would generate savings for developers “but at a far greater cost to nature – around six times higher than any savings made,” raising concerns about prioritising short-term development viability over long-term ecological outcomes.
The Trust also criticised limitations on BNG requirements for NSIPs, arguing that restricting obligations to directly impacted habitats “substantially reduces the BNG obligation” and “further erodes the overall effectiveness of Biodiversity Net Gain.”
Mark Lloyd, Chief Executive of The Rivers Trust, said:
“Housebuilding and growth do not need to be at-odds with nature recovery. Time and again evidence has shown that nature is not a blocker. In fact, a flourishing natural environment, based around thriving rivers, is essential to creating happy and healthy communities, as well as being a fundamental basis for long-term economic growth.”
“With the Government’s Environmental Improvement Plan targets rapidly approaching, we should be focussing on making Biodiversity Net Gain a stronger and more effective policy, not looking to water it down. It should also be considered that insufficient public money is available to support nature restoration at the pace and scale required, and the Government must focus efforts on urgently strengthening nature markets to draw in private sector finance.”
“The Government is proposing improved guidance and digitisation for Biodiversity Net Gain, which we had called for, but it is continuing down a path that risks stunting nature recovery despite the UK being one of the most nature deprived countries in the world.”
Balancing growth and environmental delivery
The Government’s response reflects an ongoing attempt to balance housing delivery, infrastructure development and environmental commitments under the Environment Act 2021, which made BNG mandatory for most developments in England.
While the removal of certain exemptions and the introduction of clearer thresholds have been welcomed as pragmatic steps, stakeholders across the sector are calling for faster decision-making and greater policy certainty.
As consultations continue – particularly on brownfield development and small-site thresholds – the effectiveness of BNG in delivering measurable biodiversity improvements alongside economic growth remains a central focus of debate.
