Yes. There's no upper limit in the legislation. The 10% figure in the Environment Act 2021 is a floor, not a ceiling—developers can propose whatever biodiversity uplift they like, provided it's calculated using the Defra Metric, deliverable, and secured for 30 years.
In practice, plenty of schemes already exceed 10%, particularly larger sites where ecological design gets built in early. The more interesting questions are whether local planning authorities can require more than 10%, and when exceeding the minimum actually makes sense.
The distinction between policy encouragement and legal requirement matters here.
Government guidance is clear that local planning authorities cannot change the biodiversity metric or impose a different gain hierarchy. The statutory framework applies nationally, and LPAs must use it consistently.
What they can do is encourage higher net gains through local plan policy where there's ecological justification—sites identified in a Local Nature Recovery Strategy, land affecting priority habitats, strategic growth locations with cumulative impacts. But "encourage" is doing real work in that sentence. An LPA that tries to impose 20% as a blanket requirement, without site-specific evidence, is on shaky ground.
This aligns with broader planning principles on viability and proportionality. Weston Homes v Secretary of State (2024) EWHC 2089 (Admin) confirmed that decision-makers can't apply future or aspirational standards as if they were current legal requirements. The same logic applies to locally-inflated BNG targets: if you're going to require more than Parliament set as the minimum, you need to justify it.
For some developments, going beyond 10% is genuinely strategic rather than just virtuous.
A complex or sensitive site where ecology is likely to be contentious benefits from front-loading the biodiversity commitment. It removes a potential objection, demonstrates good faith, and can accelerate decision-making. For sites near designated habitats or ecological corridors, higher gains may be the difference between an acceptable scheme and one that faces sustained opposition.
There's also the corporate angle. Developers with ESG commitments or nature-positive targets may find that individual sites need to exceed 10% to meet portfolio-level goals. And for projects where community engagement matters—which is most projects—visible ecological ambition plays better than bare compliance.
None of this means every scheme should target 20%. The calculation is site-specific: what's the ecological context, what's the cost of additional units, what planning weight will higher gains actually carry, and does the project's economics support it?
Whether you're delivering 10% or 25%, the underlying requirements are identical. Gains must be calculated using the Defra Metric. Delivery must be secured for 30 years. Off-site units need proper legal security and, where applicable, registration. Commitments become enforceable through planning conditions or conservation covenants.
Government guidance on enforcement applies regardless of the percentage. If anything, higher targets increase the importance of robust habitat management and monitoring. Committing to 20% and delivering 12% is worse than committing to 10% and delivering 10%—you've created an enforcement gap and undermined your credibility for future applications.
The practical challenge with exceeding 10% is making sure the additional commitment is deliverable at reasonable cost.
On-site delivery is usually preferable where feasible, but many sites can't accommodate significant habitat creation beyond what's needed for the baseline. Off-site units become essential, which means either securing land yourself or purchasing from a habitat bank. Either way, the legal structure matters: units need to be properly registered, the 30-year management obligation needs to sit with an entity that will exist and perform, and the costings need to reflect actual habitat establishment rather than optimistic projections.
Hybrid approaches—partial on-site delivery supplemented by off-site units—often make the most sense for schemes targeting higher gains. They allow developers to capture the placemaking benefits of on-site habitat while using off-site delivery to hit the target number efficiently.
10% is the legal minimum. You can exceed it, LPAs can encourage you to exceed it (with justification), but nobody can arbitrarily require it. Higher gains make strategic sense for some sites and some developers, but the decision should be driven by planning context and project economics rather than aspirational round numbers.
When you do commit to more than 10%, the delivery discipline matters more, not less. The enforcement framework doesn't distinguish between mandatory minimums and voluntary commitments—it just asks whether you delivered what your Biodiversity Gain Plan said you would.
Eco Capital sources BNG units through a nationwide habitat bank network, with all units registered with Natural England. For developers considering gains above 10%, that means access to certified unit supply at scale—useful when on-site delivery alone won't hit an ambitious target.
The advisory side matters here too. Eco Capital reviews baseline assessments and planning conditions to identify whether exceeding 10% makes commercial sense for a particular site, and if so, what combination of on-site and off-site delivery gets there most efficiently. Units can be reserved pre-planning, locking in supply and pricing before the Biodiversity Gain Plan is finalised.
