BNG for NSIPs: What the Environmental Improvement Plan 2025 Confirms for May 2026
Introduction
The Environmental Improvement Plan 2025 (EIP 2025) confirms that Biodiversity Net Gain (BNG) will become mandatory for Nationally Significant Infrastructure Projects (NSIPs) from May 2026. This requirement sits alongside the existing BNG framework already in place for Town and Country Planning applications.
For organisations delivering or supporting large-scale infrastructure, this update provides clarity on both timelines and expectations. The following summary outlines the key information confirmed through EIP 2025 and what this means for planning future projects.
BNG Requirement for NSIPs
EIP 2025 reaffirms that NSIPs will be required to deliver a minimum 10% Biodiversity Net Gain and comply with the BNG hierarchy. This includes:
assessing pre- and post-development biodiversity using the statutory metric
prioritising onsite mitigation where possible
delivering any remaining requirement through off-site biodiversity units or statutory credits
securing all measures for a minimum 30-year period
This brings NSIPs in line with the wider BNG system already in use across England.
Why Early Groundwork Matters
Although the requirement comes into force in May 2026, the lead-in time for BNG — particularly for large infrastructure — means early planning is essential. NSIPs typically involve:
extensive land take
complex ecological baselines
multiple local authorities or regions
high and varied habitat demands
long-term land security and management arrangements
For these reasons, early engagement with habitat providers and ecological specialists supports smoother delivery, greater certainty around unit availability, and closer alignment with planning timescales.
The Role of Off-Site Biodiversity Units for NSIPs
Given scale and land constraints, many NSIPs will need to meet part of their BNG requirement through off-site biodiversity units.
EIP 2025 reinforces the role of high-quality habitat creation in meeting national nature recovery targets. As a result, demand for:
registered gain sites
high-distinctiveness habitats
long-term management assurance
is expected to increase as NSIP schemes prepare for compliance.
How ILM Supports NSIP Preparation
Integrated Land Management provides off-site biodiversity units through multiple registered and developing habitat sites across the country.
Our team supports NSIP promoters, consultants and environmental leads with:
early discussions around unit availability
identifying suitable habitats within ILM’s existing and upcoming sites
clarity on geographic considerations such as relevant LPAs and NCAs
long-term management planning and documentation
keeping project teams informed of ILM’s expanding habitat supply as new sites progress through registration
This ensures that biodiversity considerations can be factored into the early stages of NSIP preparation and design.
Conclusion
The Environmental Improvement Plan 2025 confirms the deadline for BNG compliance for NSIPs. With May 2026 approaching, early discussions help ensure biodiversity requirements can be planned for efficiently and in line with planning and delivery expectations.
Integrated Land Management welcomes enquiries from infrastructure developers, planners and environmental consultants seeking clarity on off-site biodiversity units or future habitat supply.
FAQs: BNG and NSIPs
-
BNG becomes mandatory for NSIPs in May 2026, subject to the confirmed government timeline.
-
Nationally Significant Infrastructure Projects will be required to deliver a minimum 10% Biodiversity Net Gain. This includes the use of the statutory metric, following the BNG hierarchy and securing all measures for a 30-year period. The requirement comes into force in May 2026, as confirmed in the Environmental Improvement Plan 2025.
-
NSIPs can deliver BNG through a combination of:
onsite habitat creation or enhancement,
off-site biodiversity units purchased from registered habitat sites, and
statutory credits (only when onsite and offsite options cannot meet requirements).
-
Large infrastructure schemes typically have:
extensive land footprints,
complex ecological baselines, or
limited ability to deliver all required habitats onsite.
As a result, off-site units are often necessary to meet the full 10% net gain requirement.
-
Off-site units must be supported by:
a formal unit allocation,
a gain site registered on the national BNG register, and
a secured 30-year legal mechanism (such as a conservation covenant or Section 106 agreement),
alongside long-term management and monitoring plans.
-
Off-site biodiversity units can be sourced from registered biodiversity gain sites. ILM provides units from multiple registered and developing habitat nationally.
-
BNG considerations should begin at the early design stage. Off-site units, geographic offset requirements and habitat availability often need to be confirmed well in advance of Examination and DCO submission.
-
Unit reservation depends on site availability and project timelines. Get in touch to best understand current and upcoming habitat supply and units available for reservation on future projects.
-
ILM supports NSIP promoters and environmental teams by:
discussing available and upcoming off-site units,
identifying suitable habitats within its registered sites,
clarifying geographic considerations (LPAs/NCAs), and
providing required documentation for 30-year management and registration.
