Biodiversity Net Gain

This page provides a summary of requirements for Biodiversity Net Gain (BNG) in relation to planning applications within Babergh and Mid Suffolk.

For detailed guidance on the full BNG process, including monitoring fees, application requirements, and legal agreements, please download the BMSDC Biodiversity Net Gain Guidance Note (updated May 2026).

Biodiversity net gain (BNG) is an approach to the development and management of land that aims to leave biodiversity in a measurably better state than it was before development occurred. It will ensure habitats for wildlife are retained, enhanced and created through the development process.

Under the Environment Act 2021, all planning permissions, with a few exceptions, are required to deliver a minimum of 10% increase in the biodiversity net gain delivered compared to the pre-development baseline. BNG will be measured using Defra’s biodiversity metric and all net gains will need to be secured and monitored for at least 30 years.

These commitments are further developed in Policy LP16 of our new Joint Local Plan and in the Biodiversity Net Gain Interim Planning Guidance Note for Suffolk. More detailed guidance on BNG will also be set out in a new Biodiversity and Trees Supplementary Planning Document.

Our vision reflects the principles and proportionality of BNG as set out in Professor Sir John Lawton’s report, Making Space for Nature. The report’s main message was that we need to make our network of sites more, bigger, better and joined to protect and restore biodiversity. For us this means:

• Creating new sites
• Increasing the size of wildlife sites
• Protecting what we have, while improving its quality with better management including through buffers for wildlife sites
• Enhancing connection by creating new wildlife corridors or stepping stones;

Biodiversity Metrics - what does it assess? 

Habitat Type: The habitats present on site determined by a competent person.
Habitat Size: The area of each habitat type present on site, compared to the habitat area proposed to be retained, enhanced or created. 
Distinctiveness: A score based on the type of habitat present.
Condition: A score based on the biodiversity value of the habitat relative to others of the same type. This is determined by condition criteria set out in the technical supplement.

Householder Applications

Although mandatory BNG is not required for householder applications, our Joint Local Plan Policy LP16 states that biodiversity enhancement measures should be provided in any new development. You will be required to incorporate one or more of the following from the following Biodiversity Checklist:

• Integral bat boxes
• Integral bird boxes/bricks: Rather than generalist bird boxes, these should be tailored to priority species such as House Sparrow, Starling, Swift and others. See here for list of Priority species
• Integral bee bricks
• Green roofs/walls or Brown/"Living" roofs: These should support diverse habitats, sedum is NOT considered appropriate as it is a monoculture. For more information, click the following link: Green Roof Code
• Hedgehog friendly fencing. Please Note, this is only relevant for applications which are actually for fencing.
• Biodiversity Enhancements - Householder Development Guide

Discharging your BNG Condition

Where planning permission has been granted and this is subject to the statutory BNG condition (please see important notes on your decision notice), you will need to apply to discharge the condition.

If the proposals meet the Councils definition for significant enhancement on-site, or off-site (not statutory credits or habitat banks) this is a three step process, you will have to apply to discharge the condition before applying for the S106 application.

Further details are available via the BMSDC Biodiversity Net Gain Guidance Note

Application fees apply as follows:

(Legal fees in respect of drafting and completing the S106 Agreement, and monitoring fees will apply in addition to the application fee)