The Government has finally followed up its February 2023 consultation response on the implementation of mandatory BNG in England with a new consultation on BNG for NSIPs (the 2025 Consultation) and a new “go-live date in May 2026” (quietly abandoning its long-standing November 2025 implementation date). This briefing considers the detail set out in the consultation paper, which builds on the high level approach for applying mandatory BNG to NSIPs originally outlined in the 2022 consultation (the 2022 Consultation).
With the close of the latest consultation, we set out below what we think are five key takeaways and our thoughts on the emerging picture for mandatory BNG for NSIPs.
- The BNG regime for NSIPs will be the same for all NSIP sectors and will follow broadly the same approach as that for TCPA applications
The Government’s intention is to implement mandatory BNG for all onshore NSIPs in England in the same way because this “will be the most consistent approach”. In this regard, the 2025 Consultation sets out model text for a core biodiversity gain statement to be replicated for each NSIP sector through separate biodiversity gain statements. With the emphasis on consistency across the statements, the intention is that these will sit alongside the relevant National Policy Statement until they are next reviewed (at which point they will then be absorbed into the relevant NPS).
Although the legal framework and mechanism for securing BNG for NSIPs is tailored to the DCO regime, in substance the Government intends to follow broadly the same approach to mandatory BNG as for TCPA applications. This includes:
- The biodiversity gain objective for NSIPs being at least 10%;
- Use of the statutory biodiversity metric to calculate the requisite BNG;
- Delivery of BNG being onsite, offsite or via the purchase of statutory biodiversity credits;
- BNG being a minimum 30 year commitment; and
- Offsite BNG being registered and allocated to the project in the same way as for TCPA applications.
In particular, even though the 2025 Consultation acknowledges that “for NSIPs the development boundary may sometimes be much larger than the actual construction area”, the Government intends for all land within the DCO Order Limits to be subject to BNG (with the exception of irreplaceable habit for which a bespoke compensation plan will be required as for TCPA applications). This will include any land for temporary use during construction, albeit the consultation does recognise some of the potential complexities around this by seeking stakeholder views on whether a bespoke policy is required for such land.
- The Biodiversity Gain Hierarchy will be different for NSIPs
One key departure from the mandatory BNG regime for TCPA applications is in respect to the Biodiversity Gain Hierarchy. The Government envisages that applicants for DCOs can deliver BNG onsite or offsite in the first instance, rather than onsite BNG being the priority as per the Biodiversity Gain Hierarchy in operation for TCPA applications.
On the face of it, this is potentially helpful for NSIPs since it provides them with greater flexibility for BNG delivery. However, it appears that the Government has a different aim in mind – specifically to “ensure that applicants aren’t incentivised to use compulsory acquisition to further expand their scheme boundaries to try and deliver BNG entirely onsite”. Which takes us neatly into the next point…
- Compulsory acquisition powers for BNG will only be available in exceptional circumstances
Notably the 2025 Consultation states the following in respect to the use of compulsory purchase powers for BNG associated with NSIPs:
“Government guidance on compulsory acquisition sets out that applicants should be able to demonstrate that all reasonable alternatives to compulsory acquisition have been explored. We therefore expect that once BNG is implemented for NSIPs, the availability of off-site units and statutory biodiversity credits will mean that applicants are unlikely to use compulsory acquisition of land, whether on-site at a development or off-site elsewhere, to meet their BNG requirement unless there are exceptional circumstances.”
This position is not one that the Government has expressed before. It is, however, the natural consequence of the proposed departure from the Biodiversity Gain Hierarchy applicable to TCPA applications; after all, if onsite and offsite BNG have equal priority for NSIPs and offsite BNG can be delivered by the purchase of biodiversity units (as should always be possible in a properly functioning biodiversity units market), there should no longer be the need for the compulsory acquisition of land to achieve the preferred outcome under the applicable Biodiversity Gain Hierarchy.
The consultation does not explain what exceptional circumstances the Government has in mind to justify the use of compulsory acquisition powers for BNG purposes within a DCO. Instead further guidance on BNG and compulsory purchase is promised.
- The statutory biodiversity metric user guide will be updated
Whilst the 2025 Consultation is clear that the same statutory metric will be used for TCPA and DCO applications, it indicates that “minor updates” will be made to the associated user guide in order to “provide additional detail on how the metric can be applied for NSIPs where different approaches are needed”. An example provided in the consultation is clarifying that, where a scheme crosses multiple local planning authority boundaries, NSIPs can deliver offsite BNG in any of the relevant local authority areas without incurring a spatial risk multiplier penalty within the metric.
This suggests that, to the extent that any differences between TCPA and DCO schemes are being recognised in the BNG regime for NISPs, this may be in how the metric is applied. Plainly the updated user guide will be critical in this respect.
- Applicants will need to account for any Order Land already registered/allocated for offsite BNG
One important point of detail in the 2025 Consultation concerns how Order Land that is already registered or allocated for offsite BNG should be treated for the purposes of calculating the pre-development value of the land – rather than using the current biodiversity value of such land in the metric, the applicant must use the projected biodiversity value to be achieved.
This is something that DCO promoters will need to be alive to going forward, particularly where schemes overlap and as more land is registered/allocated for mandatory BNG over time via the TCPA and DCO processes. One broader question that this also raises is how any prospective onsite BNG associated with third party schemes falling within the Order Land should be accounted for. It is difficult to see why the same logic shouldn’t apply if the onsite BNG associated with such schemes could not be fully delivered because of a proposed NSIP.
Joining the dots: Some thoughts on the emerging BNG picture for NSIPs
Two things are immediately striking about the Government’s proposals for BNG for NSIPs set out in the latest consultation: Firstly, how little has really changed from the 2023 consultation response; and, secondly, the Government’s overriding desire to maintain consistency both with the form of mandatory BNG that has been adopted for TCPA applications and across the different NSIP sectors.
Adopting a “one size fits all” approach to mandatory BNG, of course, make sense in principle but risks being too simplistic in practice, not least because NSIPs will usually be of a different nature and scale to TCPA applications.
In this regard, making all DCO Order Land subject to mandatory BNG has the potential to generate significant BNG requirements. Additionally the change to the Biodiversity Gain Hierarchy applicable to NSIPs coupled with the proposed limitation on compulsory acquisition powers for BNG delivery means that, in practice, many DCO promoters will inevitably be reliant on the biodiversity units market. Since this is the same fledging market that currently services the offsite BNG requirements of applicants in the TCPA regime, there is the risk of unintended consequences here: That once mandatory BNG for NSIPs goes live the demand for offsite BNG will outstrip supply causing resultant issues for applicants within both the TCPA and DCO regimes. This, in turn, may inadvertently push applicants in both regimes towards the Government’s least preferred option of buying statutory credits.
The only nod to the geographical scale of NSIPs in the 2025 Consultation is in fact the Government’s promise to update the statutory biodiversity metric user guide to clarify how the spatial risk multiplier penalty will work where a project crosses multiple local authority boundaries. Whilst that update will be helpful as far as it goes, the fact that the spatial hierarchy will otherwise clearly still apply to NSIPs risks exacerbating the strain on local biodiversity units markets, particularly in infrastructure “hot spots”. Query why the spatial hierarchy, which incentivises local delivery of offsite BNG, is relevant to NSIPs at all if these projects are, by definition, nationally significant? There is a case for not just relaxing the spatial hierarchy but for disapplying it to NSIPs altogether.
Whether the Government has the appetite for any changes of this nature is questionable because the 2025 Consultation itself states that part of its purpose is to provide “more information for developers and decision makers on what will be expected on BNG after May 2026, helping them better prepare for go-live”. Even so, nothing is set in stone just yet and we will have to wait and see what the Government does next, not just in terms of consultation response but also in respect to the plethora of guidance and templates that will help shape the new regime and which is to follow.
If you would like to know more about BNG or otherwise require any assistance, please do not hesitate to contact Michael Dempsey.
