BNG for NSIPs: What the November 2026 Deadline Means for Your Infrastructure Project

If you are promoting or developing a major infrastructure project in England, a firm deadline is now in place. From 2 November 2026, Biodiversity Net Gain (BNG) becomes mandatory for Nationally Significant Infrastructure Projects. Applications submitted on or after that date must demonstrate a minimum 10% net gain in biodiversity as part of their Development Consent Order (DCO) application.

That is not far away. And if your baseline ecological surveys have not started, you may already be behind.

What is BNG and why does it apply to NSIPs?

Biodiversity Net Gain is a legal requirement embedded in the Environment Act 2021. Since February 2024, most development under the Town and Country Planning Act has had to demonstrate that it leaves the natural environment in a measurably better state than before construction. The NSIP extension brings large-scale national infrastructure projects into the same framework.

NSIPs include major roads, railways, energy generation and transmission networks, water infrastructure, and ports. These are projects consented through the Planning Act 2008 via a Development Consent Order rather than through the standard planning system. From November 2026, they will be subject to the same core BNG obligation: a 10% minimum gain, secured for at least 30 years.

The requirement applies uniformly. There are no sector-specific exemptions. Road, rail, energy and water promoters face the same obligation.

What the rules actually require

The confirmed framework contains several important details that infrastructure developers need to understand now.

Why the timeline is tighter than it looks

The November 2026 date may feel like there is time in hand. For most projects, there is not.

Breeding bird surveys run from April to July. Bat surveys require multiple visits between May and September. Great crested newt surveys have a narrow optimum window in spring. If your site has not been surveyed this season, your next realistic opportunity for a full baseline is spring 2027 — after the mandatory deadline has passed.

Applications submitted in November 2026 are being scoped and designed right now. Ecology needs to be part of that process from the earliest stages of site selection and layout, not added once scheme design is complete. The government has made this explicit: BNG considerations must be factored in throughout the project lifecycle, starting at the conception and promotion phase.

Procurement of off-site units at the scale typical of NSIPs also takes time. Identifying registered providers, negotiating agreements, and aligning habitat types with your metric requirements is not a quick process. Leaving it until late in the pre-application phase creates real risk of delay.

What developers should be doing now

If your project falls within scope, these are the four steps to take before the survey season closes.

1. 1

   Appoint a qualified ecologist immediately

   Your ecologist will scope the baseline surveys needed, identify seasonal constraints, and advise on site selection from a biodiversity perspective. Early appointment means you can schedule surveys this season rather than next year.
2. 2

   Commission your baseline ecological surveys

   The pre-development baseline is the foundation of your entire BNG assessment. The biodiversity metric calculates the units you start with, and everything else follows from that figure. Delays to the baseline delay everything downstream.
3. 3

   Engage your planning team on BNG boundary mapping

   Defining what falls inside and outside your BNG boundary is a technical and strategic exercise. It shapes the scale of your obligation and the volume of units you need to deliver or procure. This is not something to resolve late in the pre-application process.
4. 4

   Begin scoping off-site options in parallel

   Even if your scheme is well-suited to on-site delivery, understanding the off-site market in your local authority areas gives you options. The NSIP framework allows you to aggregate off-site gains across any of the local planning areas your project is located in, without triggering spatial risk multiplier penalties.

The bigger picture

BNG for NSIPs represents a significant opportunity as well as an obligation. Infrastructure projects operate at a scale where strategic habitat creation can deliver genuine landscape-level biodiversity benefits — far beyond what individual housing sites can achieve. The government expects the NSIP regime to funnel meaningful private capital into the off-site unit market and to drive habitat restoration at scale.

Projects that plan for biodiversity early and build it into scheme design will move through the DCO process more smoothly. Those that treat it as a late-stage compliance exercise will face delays, cost overruns, and the risk of late-stage redesign.

The deadline is November 2026. The window for action is now.