Biodiversity Net Gain: when conditions are used and when legal agreements are required

Biodiversity Net Gain (BNG) is secured through the planning system using a combination of planning conditions and legal agreements. While local planning authorities have discretion in how BNG is secured, that discretion is guided by statutory requirements, policy expectations and emerging best practice. Understanding when conditions are appropriate and when a legal agreement is required is important in managing risk, cost and delivery.

The legal framework for securing BNG

The statutory requirement for BNG requires not only that net gain is demonstrated at the point of decision, but that it is secured and maintained for a minimum period, typically 30 years. The planning system must therefore ensure that biodiversity enhancements are delivered and remain in place for the required duration.

This requirement shapes the mechanisms used to secure BNG.

Use of planning conditions

Planning conditions are commonly used to secure BNG where biodiversity measures are to be delivered entirely within the red line boundary of the development site and where long-term management can be controlled through the permission itself.

Conditions are typically used to:

• require submission and approval of a biodiversity gain plan
• secure the implementation of on-site habitat creation or enhancement
• control the timing of delivery
• require ongoing monitoring and reporting

For smaller or more straightforward developments, particularly where on-site provision is sufficient, conditions are often the most proportionate and efficient mechanism.

Conditions are generally favoured where the developer retains control of the land for the duration of the management period and where enforcement can be achieved through the planning regime alone.

Use of legal agreements

Legal agreements, most commonly planning obligations, are used where biodiversity net gain relies on off-site provision or where long-term management cannot be adequately secured through conditions alone.

Legal agreements are typically required where:

• biodiversity units are delivered on land outside the application boundary
• land is not controlled by the applicant in the long term
• third-party landowners are involved
• complex management or monitoring arrangements are required
• enforcement needs to bind successors in title

Legal agreements provide a more robust mechanism for securing long-term delivery.

Disclaimer
This article is provided for general information only and does not constitute planning advice. Planning matters are site-specific and subject to change. Professional advice should be sought before taking action in relation to any particular site or proposal.