Biodiversity Net Gain

Our biodiversity net gain work so far

The Buckinghamshire and Milton Keynes Natural Environment Partnership is working with its partners to put into place a robust and transparent scheme for ensuring that development results in net biodiversity gains across the Bucks and MK area.

We have successfully appealed for the Local Plans in the area to commit to net biodiversity gain and commit to the “mitigation hierarchy” – i.e. that all development seeks to avoid and then minimise impacts on biodiversity on-site as a priority, and only seeks offsite-offsets for biodiversity losses once all opportunities on-site have been exhausted.

Over the past few years, the NEP has worked alongside Warwickshire County Council, which has experience of running a successful biodiversity net gains system since the national pilots in 2012, to develop a process for the Buckinghamshire and Milton Keynes area, to offer to the local planning authorities. National policy has developed hugely over this period, and as a result so has the work of the NEP to develop the processes needed and offered.

We have most recently been assisting and advising Buckinghamshire Council on its internal work and processes that will be required to operate the biodiversity net gain system, raising issues and decisions requiring discussion and agreement, for example, based on areas coming up in new national and developing policy, and writing a clear guidance document on the proposed NEP scheme as to how it could work in Buckinghamshire.

Our work has also included:

Feasibility study (2019) – paper review for developments in Bucks and MK

This work took a sample of 59 recent planning applications of various types across Bucks and MK to identify, in the main i) whether development size thresholds were appropriate for requiring net gain (concluded that biodiversity losses could occur on any development, and were not dependent on size / development type); and ii) likely resource implications for a local authority.

Download the Feasibility Study (2019).


Model Supplementary Planning Document (version 2) – released January 2021

Our original (March 2020) and updated (February 2021) model SPDs were developed by the NEP partners to set out the detailed workings of the NEP-developed approach and system to providing biodiversity net gain in line with strategic biodiversity priorities in the area. The latest version was used by Buckinghamshire Council to inform its own SPD for public consultation in 2021. The NEP has since then provided ongoing advice to Buckinghamshire Council based on more recent reviews of changing and development government policy in this area, including the national metric 3.0 guidance released in July 2021. Buckinghamshire Council is currently working to finalised its SPD for release. (The NEP’s latest model SPD should, therefore, be read alongside new updates from government on emerging policy; for example the use of the latest available national metric by default).

Download our model Supplementary Planning Document, version 2, here.

Priority offset location mapping

In February 2021, the NEP Board approved the NEP’s biodiversity accounting working group’s priority offsetting mapping report. This work was produced with guidance and assistance from Warwickshire County Council, to be used to assist with the selection of the location of biodiversity offset sites, to be used alongside other criteria. The full report includes the methodology followed, and the resulting guidance map, Map 10, is on page 22. The mapping work aims to prioritise, where possible, and in consideration with other criteria, offsetting within the Biodiversity Opportunity Areas; and otherwise in areas that buffer them, or provide linkages within and between them.

Download the Priority Offsetting Mapping Report here.


Frequently Asked Questions

The NEP has fed into the Q&As being collated and continually updated by the Planning Advisory Service, available nationally. We would recommend reviewing the PAS pages for these and other information and advice on biodiversity net gain and preparing for the new system, which is expected to become mandatory at the end of 2023. You can find this information on the following link:

If you have further questions about how net gain will work in Buckinghamshire, please contact Buckinghamshire Council:

Input and advice from Warwickshire County Council

We have worked closely with advisors from Warwickshire County Council as we have developed the approach to operating a net gain system locally.  This work has involved:

  • Identifying several possible offset sites as a means of ensuring a supply of offsets;
  • Designing and end-to-end system to provide an option for developers to pay a financial contribution to discharge their offset obligations, for the local planning authority to then find and invest in the appropriate offset;
  • Advising on the development of the relevant processes and documentation that arise from the proposed method and scheme for the financial contribution to work;
  • Providing initial estimates of unit costs and a financial calculator for the Buckinghamshire area, based on Buckinghamshire Council wishing to take forward the NEP’s proposed scheme;
  • Assisting with a NEP working group of our partners to consider and review various issues and sharing lessons learned;
  • Review of emerging and updated government guidance on the requirements of the upcoming mandatory biodiversity net gain system.

Looking ahead – the NEP’s Expert Technical Advisory Panel for offset location

Part of the proposed NEP system for offsetting includes the use of an Expert Technical Advisory Panel, to ensure that any biodiversity offsets required via the developer financial contributions to the NEP-designed system, are located according to biodiversity priorities and needs across Buckinghamshire and Milton Keynes.

The proposal would involve the Expert Panel regularly reviewing biodiversity offset requirements and recommend to local planning authorities the best available match with available biodiversity net gain schemes to contribute towards broader biodiversity objectives and priorities across the area.  Selection would also be based on other criteria that are in development (e.g. compliance with s106 obligations / other relevant agreement that the offset is linked to: alignment with local biodiversity priorities; proximity to area of loss; the location, habitat type and units available in local offset schemes; project lifespan; additionality; and deliverability.)

The NEP is now waiting to hear whether Buckinghamshire Council would still like to go ahead with this process, given the release of more recent Government guidance and propositions (per the BNG consultation) and changing and emerging national preferences as to how net gain requirements should be delivered.

We support the efforts of both Buckinghamshire and Milton Keynes Councils as they embark on ensuring biodiversity net gain from development.

If you would like more information about biodiversity net gain and how it will operate in Buckinghamshire, please contact Buckinghamshire Council:

Response to the Government’s Biodiversity Net Gain public consultation (April 2022)

Using our experience so far, the NEP has responded to the Government’s 2022 consultation on the proposals for the regulations and implementation of Biodiversity Net Gain. Whilst we continue to support a system to require a minimum 10% net biodiversity gain, we are concerned about a number of the Government’s proposals, some of which could limit the benefit for biodiversity as well as risk effectively undoing the extensive work we have carried out over the last few years. We remain hopeful for further dialogue and policy development within Government to allow the scheme we have designed collectively to be provided as a one-stop shop option for developers locally while also meeting strategic biodiversity priorities and needs.

Our full response is available here.