Since February 2024, most developments in England have needed to deliver a minimum 10% measurable uplift in biodiversity, maintained for at least 30 years. This isn't a planning policy preference—it's a statutory requirement under the Environment Act 2021, embedded directly into the Town and Country Planning Act through Schedule 7A.
Developers, landowners, and their advisers increasingly want to know what happens when BNG commitments fall short. The short answer: planning enforcement and contractual remedies. The longer answer is more interesting, and worth understanding before you find yourself on the wrong end of it.
The biodiversity gain condition is a pre-commencement condition. Development cannot lawfully begin until the local planning authority approves your Biodiversity Gain Plan. This catches people out more than it should.
You can hold a valid, unconditional planning permission and still be legally unable to break ground. If your off-site units aren't properly secured, or your baseline assessment is incomplete, or your 30-year management arrangements are unclear, the LPA can (and should) refuse to approve the Plan. No approved Plan, no lawful start.
The Gain Plan needs to demonstrate the baseline biodiversity value using the Defra Metric, how you'll achieve the 10% uplift, how off-site units or statutory credits are secured, and what the 30-year management arrangements look like. GOV.UK's planning practice guidance sets out the requirements in detail.
Once your Biodiversity Gain Plan is approved, its commitments become enforceable planning obligations. LPAs are expected to monitor delivery and act where commitments aren't met.
If habitat creation doesn't happen, or management falls short, authorities can issue Breach of Condition Notices under section 187A of the Town and Country Planning Act. They can require corrective works. They can take court action. None of this is theoretical—it's the same enforcement toolkit used for other planning breaches, applied to a new type of condition.
Government guidance on BNG enforcement confirms this expectation.
Where biodiversity gain is delivered off-site, it must be secured through either a section 106 planning obligation or a conservation covenant under Part 7 of the Environment Act.
Section 106 agreements are enforceable by the local planning authority, ultimately by injunction. Conservation covenants are enforceable by a designated responsible body—Natural England, a local authority, or certain conservation charities—with court remedies available for breach. Guidance for responsible bodies sets out how this works.
The point is that if habitat management fails or someone ignores their commitments, enforcement doesn't depend on goodwill or reputation. It's legally actionable by bodies with statutory authority to pursue it.
BNG is designed to produce measurable outcomes over 30 years, not a one-off mitigation payment. Biodiversity Gain Plans and their associated legal agreements typically include habitat management prescriptions, monitoring schedules, reporting requirements, and mechanisms for addressing underperformance.
This is how compliance gets demonstrated. An LPA reviewing whether to take enforcement action will look at monitoring data. A responsible body considering covenant enforcement will look at monitoring data. The absence of monitoring doesn't create ambiguity in your favour—it creates evidence of non-compliance.
One feature of the BNG regime worth noting: government guidance confirms that the biodiversity gain condition cannot be varied or removed using a section 73 application. Once it's on a permission, it stays there. You can't later argue the condition is unreasonable, or that circumstances have changed, or that you'd like to pay someone off instead. The 30-year commitment is meant to be exactly that.
The courts have started to address how BNG fits into planning decisions. In Weston Homes v Secretary of State (2024) EWHC 2089 (Admin), the High Court confirmed that BNG requirements must be applied according to the law in force at the relevant time—but also reinforced that where BNG does apply, it's a material and enforceable consideration.
As the regime beds in and more decisions get challenged, we'll see clearer boundaries around what LPAs can require and what developers must deliver. For now, the direction is clear: BNG is treated as a serious planning obligation, not a box-ticking exercise.
The enforcement framework has practical implications for how BNG delivery should be structured:
Obligations run for 30 years. If you're a developer, the entity holding the obligation needs to exist and be capitalized for that period. If you're a landowner entering a conservation covenant, you need to understand what you're binding yourself (and future owners) to. If you're advising either, the legal agreements need to actually work—not just look plausible at the planning application stage.
Poorly structured arrangements create long-term exposure. An off-site provider who can't deliver, a management plan that doesn't match habitat conditions, a covenant with an inactive responsible body—these become problems years after the development completes, when the people who made the original decisions have moved on.
The flip side is that well-structured BNG delivery should be relatively straightforward to demonstrate compliance with. Clear baselines, defensible metrics, genuine habitat management, regular monitoring, proper legal security. None of this is complicated in principle. It just requires treating BNG as the 30-year legal commitment it actually is.
EcoCapital supplies off-site BNG units through a nationwide network of habitat banks, all registered with Natural England. For developers who can't achieve 10% on-site, that means units that are already certified and LPA-ready—no delays waiting for habitat bank registration or worrying about whether the paperwork will satisfy the planning authority.
Beyond unit supply, EcoCapital advises on BNG strategy: reviewing baseline surveys, identifying the most cost-effective compliance route, and ensuring the legal structure will hold up over the 30-year term. Units can be reserved pre-planning, so developers aren't scrambling to secure supply after permission is granted.
