BNG for NSIPs is here: what changes for infrastructure developers?

Mandatory biodiversity net gain (BNG) now applies to nationally significant infrastructure projects (NSIPs), bringing greater rigour to how biodiversity is considered through the Development Consent Order (DCO) process.

To mark the introduction of the new regime on 2 November 2026, TLT brought together Angus Walker, Partner at TLT, Nick White, BNG lead at Natural England, and Mikyla Davidson, lead DCO project manager at RWE, to explore what it means in practice.

While BNG has already been expected for DCO applications, the mandatory regime is stricter on achieving the required 10% biodiversity gain, trading rules and documentary requirements.

BNG needs to inform project design

From an NSIP developer's perspective, Mikyla Davidson emphasised the importance of embedding BNG into project design from an early stage. Developers need an early understanding of their biodiversity baseline, where losses can be minimised and where gains can realistically be delivered as the design develops. That understanding also needs to evolve with the project. Design and construction changes during project examination can have knock-on effects for BNG calculations, so biodiversity implications need to be kept in mind as an application progresses. Mikyla also highlighted that BNG should be treated as a whole-life project consideration, with implications for land, cost, construction and the long-term management of habitat commitments.

Some projects such as solar DCOs will have greater scope to accommodate improvements within the development itself, while others may need to secure off-site biodiversity units.

How is BNG different for NSIPs?

As Angus Walker explained, the regime has been adapted to reflect the particular characteristics of major infrastructure projects, including large areas of land, temporary construction requirements and multiple local authority areas.

In particular, not all land within DCO order limits needs to form part of the BNG baseline calculation. The biodiversity gain plan securing BNG is also dealt with in three stages rather than one.

These adaptations provide flexibility, but the mandatory regime brings firmer requirements around percentages, trading rules and documentation. For promoters, early planning will be critical.

What could NSIPs mean for the BNG market?

The discussion also highlighted potential wider implications as major infrastructure projects enter the regime.

Where gains cannot all be delivered within a development, projects may need to purchase off-site biodiversity units. NSIPs could therefore become significant purchasers, adding a new source of demand alongside developments already subject to BNG under the town and country planning system.

Nick White reflected on what has happened since BNG was introduced for town and country planning in February 2024, including the international interest the English regime has attracted. He also highlighted the potential local benefit: BNG delivered close to a project can provide a community benefit that helps make the development more acceptable locally.

The subsequent discussion centred around Local Nature Recovery Strategies, surplus biodiversity units and whether habitat land could later be used for an expansion of the development. Together, this underlined the importance of considering BNG alongside the wider and longer-term development of an NSIP.

For developers entering the mandatory regime, the message is straightforward: understand the baseline early, build BNG into design, keep calculations under review and establish how the required gains will be delivered.

BNG is now another important consideration in an already complex DCO process. The key is making it part of the decisions that shape a project from the outset.

This article draws on insights shared at TLT's BNG for NSIPs launch event on 2 November 2026, featuring Angus Walker of TLT, Nick White, BNG lead at Natural England, and Mikyla Davidson, lead DCO project manager at RWE.

This publication is intended for general guidance and represents our understanding of the relevant law and practice as at November 2026.  For more information see our terms & conditions.