Achieving net gain for biodiversity - guidance for developers

Find out what our requirements are for developers to improve biodiversity (known as Biodiversity Net Gain). 

All developments are required to achieve a minimum 10% Biodiversity Net Gain, apart from a few exemptions outlined on GOV.UK. The Environment Act 2021 mandated this requirement for Major planning applications submitted on or after February 12 2024, and 2 April 2024 for certain other planning application types.

This guidance has been produced to explain to developers:

  • the level of net gain for biodiversity that is expected in Leeds
  • what written information you need to submit with planning applications to assess the measurable Biodiversity Net Gain
  • what measures will be required if you cannot achieve 10% Biodiversity Net Gain On-site
  • the role of Leeds City Council as the monitoring and reporting body for Biodiversity Net Gain

What is Biodiversity Net Gain?

Biodiversity Net Gain is defined as delivering more or better habitats for biodiversity and demonstrating this through use of the Statutory Defra Biodiversity Metric.

It encourages development that delivers biodiversity improvements through habitat creation or enhancement after avoiding or mitigating harm. Biodiversity Net Gain involves an approach whereby developers work with stakeholders to support their biodiversity goals.


We already have a Core Strategy Policy (G9, page 112) which requires a net gain for biodiversity from development. The National Planning Policy Framework (paragraph 185 b) requires net gain to be achieved in a measurable way and includes Planning Practice Guidance on net gain (paragraphs 20 to 28).

There is an emerging Biodiversity Net Gain Policy in the Leeds Local Plan Update and Biodiversity Net Gain Planning Practice Guidance which helps to explain how the Environment Act 2021 primary and secondary legislation should be implemented through the planning process.

Along with other public bodies, Leeds City Council has a Biodiversity Duty under the Natural Environment and Rural Communities Act 2006. The emerging Local Plan Update Biodiversity Net Gain policy has been written to be in synergy with both the Environment Act 2021 and the UK Government’s 25 Year Environment Plan.

The following objective from the 25 Year Environment Plan is particularly pertinent to the Leeds district – and forms a common thread running through this guidance:

Enhancing beauty, heritage and engagement with the natural environment by making sure that there are high quality, accessible, natural spaces close to where people live and work, particularly in urban areas, and encouraging more people to spend time in them to benefit their health and wellbeing.

This guidance is strongly underpinned by:

The CIRIA (Construction Industry Research and Information Association) Biodiversity Net Gain Good Practice Principles for Development.

Our requirements

We are seeking a minimum 10% Biodiversity Net Gain through use of the Statutory Defra Biodiversity Metric – and the net gain must be meaningful as well as measurable. From the earliest stage proposals for new development should involve competent and experienced ecologists inputting into the various design and layout options to enable the minimum 10% Biodiversity Net Gain to be delivered On-site. Where this is clearly demonstrated not to be feasible (to be agreed with the Local Planning Authority) it may involve Off-site compensation.

The Local Planning Authority (LPA) will expect all applications to conform to this guidance to achieve consistency of information on which to carry out decision-making in a timely manner. Not following this guidance may lead to delays to the processing of your planning application, as the LPA requests further evidence that both a measurable and meaningful net gain is being achieved.

In seeking to ensure that the requirements for Biodiversity Net Gain are achieved, it is important that these issues are addressed at a very early stage in the application process. Consequently, applicants are encouraged to engage in the Pre-application enquiry service.

What are the Biodiversity Net Gain Good Practice Principles for Development?

There are numerous different ways that Biodiversity Net Gain can be achieved, one of these is to simply apply the Metric to an already designed layout and see what the numbers tell you. It is possible this approach will give you enough “numbers” to demonstrate you can achieve the minimum 10% net gain in biodiversity. However, Biodiversity Net Gain is more than just achieving biodiversity-by-numbers.     

The "Good Practice Principles for Development" provide an industry-standard having been produced from a range of the UK’s most respected professional bodies. They provide a way for industry to prove that development projects have followed best practice.      

These 10 Principles set out good practice for achieving Biodiversity Net Gain and must be applied together as one approach. It will be important to demonstrate against every Good Practice Principle that is has been considered and is being achieved. If only 9 out of 10 Principles are being achieved then Biodiversity Net Gain is not being achieved.      

How can you demonstrate Biodiversity Net Gain has been fully considered at the outset?

The objective should always be to deliver 10% Biodiversity Net Gain On-site and therefore it will be essential to appoint a competent and experienced ecological consultant at the earliest stage to be involved in the iterative design stage of the layout. The ecological consultant should work closely with the landscape architects and urban designers to consider which options of the layout lead to the best possible outcome for achieving Biodiversity Net Gain On-site.     

This type of information should be included as part of and as a clearly distinguishable annex to the Design and Access Statement (if one is produced) or as a stand-alone assessment whereby different options of layout are shown with their corresponding different Biodiversity Unit outcomes. Where the layout resulting in the lowest impact on biodiversity has not been taken forward to the proposed layout stage an explanation should be provided why this option has been chosen over another.      

Evidence should be submitted as part of the Ecological Impact Assessment to demonstrate the ecological consultant has been involved in the initial design stage of the layout in a meaningful way. This should include reference to the mitigation hierarchy of: avoiding damage to sensitive ecological features; minimising impacts on such sensitive ecological features; and where these first two steps cannot be achieved (with an explanation to justify why not) finally consider what level of compensation will be required either On-site or Off-site (or both).     

What information do you need to submit for validation?

The following information must be submitted to allow the LPA to validate the application:     

Biodiversity Net Gain Statement with written confirmation that:     

  • Mandatory Biodiversity Net Gain does or does not apply
  • Whether any habitat degradation has taken place before or after the Biodiversity Metric calculations were carried out

The Statutory Biodiversity Metric with:     

  • Baseline and Post-development calculations fully completed (Outline applications may provide indicative Post-development calculations)
  • Date of Metric completion
  • Name of competent and/or Watercourse accredited person

A Map showing:     

  • On-site habitat (using UK Habitat Classification) and any irreplaceable habitat

What information do you need to submit before Determination?

In addition to any other information on the Biodiversity and Planning web page, the following information should be submitted as soon after Validation as possible to allow a timely consideration before Determination:      

An accurate, scaled map/s showing:     

  • Where Significant On-site Biodiversity Net Gain is proposed – labelled to confirm a Landscape and BNG Management Plan will apply to this area
  • Any habitats to be retained or enhanced – labelled to confirm a Biodiversity Construction Environmental Management Plan will apply to this area
  • Where Baseline and Post-development Biodiversity Units will occur On-site showing both UK HAB parcels and corresponding numbers of Biodiversity Units
  • Any Off-site parcels of land proposed to deliver Biodiversity Units with Baseline and Post-development UK HAB parcels and corresponding numbers of Biodiversity Units

Written justification:     

  • that all 10 Biodiversity Net Gain Good Practice Principles have been considered and can be achieved – this could be in a table format with a column for justifying the measures in place to achieve each Principle (not just a tick).
  • demonstrating the habitat creation and/or enhancement measures to achieve numbers of Biodiversity Units
  • explaining who will be responsible for funding the initial habitat creation/enhancement works, long-term management and habitat monitoring
  • explaining who will be responsible for implementing initial habitat creation/enhancement works, long-term management and habitat monitoring

Condition Assessment sheets for each habitat parcel surveyed based on:     

  • Botanical surveys at an appropriate time of year i.e. grassland surveys between May and September with sufficient quadrat survey data to demonstrate species diversity and abundance
  • Removal of grazing for at least 6 weeks prior to any botanical surveys for grasslands

Design and Access Statement (where produced) showing:      

  • A section demonstrating feasibility of different layout options to deliver 10% Biodiversity Net Gain On-site
  • Different Biodiversity Unit outcomes based on different layout options

What level of Biodiversity Net Gain is required?

The Environment Act 2021 requires a minimum of 10% Biodiversity Net Gain, and the Biodiversity Metric allows private gardens to be allocated a modest Biodiversity Unit value (if Vegetated Garden is selected) towards this minimum target. However, in Leeds 10% Biodiversity Net Gain must be on land that is capable of being covered by planning conditions or a planning obligation to secure its delivery and long-term management.      

Any scores afforded to private gardens must be in addition to the 10% Biodiversity Net Gain i.e. residential schemes that apply scores to private gardens may require 11% or more Biodiversity Net Gain to take into account the scores permitted by the Metric for private gardens.     

The category of Unvegetated Garden (with a zero score) in the Biodiversity Metric is recommended for private gardens in order to avoid applying a score but enable physical areas of land to match between Baseline and Post-development scores.     

What if degradation of habitat has occurred before determination?

If habitats are deemed to have been degraded before submission (or even after submission but prior to determination) then aerial photos (or other available evidence) will be used to decide the habitat type and an assumption of the highest scoring Condition category applied.     

What if the land covered by the application includes a nature conservation designated site or irreplaceable habitat?

Land covered by a nature conservation designation or which meets the definition to be considered a Habitat of Principal Importance will be afforded protection under Local Plan Policy G8 – which also applies to the Leeds Habitat Network. The presumption should be for full retention of any land covered by a nature conservation designation or Habitat of Principal Importance, and any impacts (such as indirect impacts) will need discussing early in the process with the LPA as bespoke compensation outside of Biodiversity Net Gain may be required.      

Irreplaceable habitats are also afforded extra protection as per the NPPF, and indirect impacts also need discussing with the LPA and bespoke compensation agreed if necessary.     

Recreational impacts and decreased water quality discharge to local watercourses are specific indirect impacts that may need to be considered.      

Where ecological reports indicate that part of an application site may meet the West Yorkshire Local Wildlife Sites Criteria it will be expected that sufficient survey information will be gathered and the site will be assessed against the relevant Criteria as part of the Ecological Impact Assessment - and retained accordingly where the Criteria are met. Any positive enhancement mitigation/compensation included in the Metric to be delivered on land meeting the Local Wildlife Sites Criteria will need to be discussed with the LPA.      

What Strategic Significance scores should be used for On-site?

High = Nature Conservation Designations or Leeds Habitat Network      

Medium = immediately adjacent to the above locations (i.e. physically connected)     

Low = anywhere else in the District     

What is Significant On-site Biodiversity Net Gain?

Unless otherwise agreed with the LPA, Significant On-site Biodiversity Net Gain will apply to a total (Habitats, Hedgerows and Watercourse Biodiversity Units added together) of 5 or more Biodiversity Units being delivered On-site in areas to be covered by the Landscape and BNG Management Plan. These Biodiversity Units can consist of features being retained, created and/or enhanced.      

Note that such Biodiversity Units can not form part of the private curtilage (such as private gardens, or hedgerows forming part of private boundaries) as delivery in those parts of the site will not be appropriate to secure as part of a management plan through planning conditions.      

How will Significant On-site Biodiversity Net Gain delivery be secured?

Protection through the construction phase, habitat creation, long-term implementation of management works and habitat monitoring of Significant On-site Biodiversity Net Gain will be secured through appropriately worded planning conditions as follows:     

  • Biodiversity: Construction Environmental Management Plan to protect any features stated as being retained or enhanced
  • Implementation Landscape Details to agree the initial soft landscaping/biodiversity works
  • Landscape Verification Report to provide evidence the initial soft landscaping/biodiversity works have been implemented before completion of development
  • Landscape and Biodiversity Net Gain Management Plan for a minimum of 30 years, starting after completion of development, to guide implementation of management actions through updated annual work programmes
  • Habitat Monitoring for a minimum of 30 years, starting after completion of development, to demonstrate delivery of the target numbers of Biodiversity Units

How are Watercourses dealt with in the Biodiversity Metric?

Watercourses cover a variety of features associated with slow-moving and flowing water – and includes wet ditches (which contain water for at least 4 months per year), small streams and covered culverts. If there is a watercourse within 10 metres of the planning application boundary (or within 5 metres of a wet ditch) a River Condition Assessment must be carried out by an accredited ecologist and that person must be named on the Start Page of the Biodiversity Metric that is submitted.     

If the watercourse is a Priority Habitat (Section 41 Habitats and Species) then it needs to be entered into the Biodiversity Metric as Very High Distinctiveness. This will apply to the River Wharfe, Leeds-Liverpool Canal where designated as SSSI and Local Wildlife Site and other sections of watercourse meeting Priority Habitat criteria.      

What is a Landscape and Biodiversity Net Gain Management Plan?

The minimum 30-year period of Biodiversity Unit delivery must be covered by a management plan for that length of time and only starts once development is completed. The purpose of the management plan is to demonstrate how the target numbers of Biodiversity Units will be achieved. It should be written in a format that has a Vision, Aims and Objectives – and then a list of Actions against each Objective.     

Having an Annual Work Programme with a clear list of management actions per month is essential to gauge success of the management plan.     

The Landscape and Biodiversity Net Gain Management Plan will be required for all applications delivering Significant On-site Biodiversity Net Gain, and any Off-site Biodiversity Net Gain. An exception to this could be where less than 5 Biodiversity Units are being delivered On-site but there is Priority habitat being retained or created (in which case the Landscape and Biodiversity Net Gain Management Plan and habitat monitoring will be required).      

Where less than 5 Biodiversity Units are being delivered On-site there may be a standard Landscape Management Plan condition attached instead – this will not normally require habitat monitoring or progress reports to be sent to the LPA.     

When is “Completion” of development?

Completion of development is not just when built structures and hard landscaping have been completed On-site but must also include full implementation of any initial soft landscaping works as well - and will then mark the start of Year 1 of the 30-year Landscape and Biodiversity Net Gain Management Plan and Habitat Monitoring time period.      

The Landscape Verification Report condition (see below) confirms completion of development has occurred in relation to initial soft landscaping works.     

Where there have been unplanned delays to habitat creation or enhancement there may need to be a revised Metric submitted to reflect the delay in starting habitat creation or enhancement – which may require additional Biodiversity Units to be delivered.     

What is the Landscape Verification Report?

The Landscape Verification Report is required by a planning condition and confirms that all the soft landscaping (which includes any initial habitat creation works) have been implemented. The Landscape and Biodiversity Net Gain Management Plan and habitat monitoring is now able to commence and continue for a 30-year period.      

Who is the Landscape and Biodiversity Net Gain Management Plan intended for and who delivers it?

Consideration needs to be given to the key users of the management plan when it is written. It must be sufficiently detailed to allow whoever is carrying out the maintenance to know what needs to be done, where and when. However, where the land is On-site and is a residential application (and the local residents are expected to pay or contribute towards its implementation) it also needs to be easily understood by the residents who use those On-site areas of land for recreation.     

Schemes delivering Significant On-site Biodiversity will be expected to provide interpretation panels explaining the biodiversity features present and also referring to the existence of the management plan so that any users of the site (nearby residents and/or workers) understand and support the management regime.     

Is there any management plan progress or habitat monitoring expected to see if the Biodiversity Net Gain is being achieved, and who pays for it?

If there is Significant On-site Biodiversity Net Gain or any Off-site Biodiversity Net Gain then a management plan and habitat monitoring is required for at least 30 years after completion of development. Planning conditions and/or a s106 will be used depending on whether the Biodiversity Units are being delivered On-site or Off-site.     

The Landscape and Biodiversity Net Gain Management Plan will have an Annual Work Programme and this will need to be sent to the LPA as a progress report for each of the first 5 years to demonstrate that the management actions are being implemented. An updated management plan should also be sent to the LPA every 5 years.      

As well as progress reports for the implementation of the management plan, there will need to be habitat monitoring by the appointed ecologist in years 1,3,5,10,20 and 30.     

The management plan should include details of who is responsible for funding and carrying out the management works for the 30-year period, and also for funding and carrying out the habitat monitoring.     

What is the Monitoring and Reporting Body role?

In Leeds, the LPA is taking an active role in overseeing implementation of Biodiversity Net Gain for any Significant On-site Biodiversity Units and all Off-site Biodiversity Units. This will allow the LPA to know whether Biodiversity Units are being achieved resulting from granted planning permissions and refer to these in periodic reporting to the Secretary of State under the Environment Act 2021.     

This does not mean the LPA will be carrying out habitat monitoring, that is the responsibility of the developer, landowner or private habitat banks etc.     

Instead, it means there will need to be submission and approval of:     

  • the 30-year Landscape and Biodiversity Net Gain Management Plan
  • progress reports for each of the first 5 years demonstrating the annual work programmes have been implemented
  • an updated Landscape and Biodiversity Net Gain Management Plan every 5 years
  • habitat monitoring reports with Condition Assessments for years 1,3,5,10,20 and 30

Where the management plan progress reports or habitat monitoring show that the previously approved numbers of Biodiversity Units are not being delivered to the satisfaction of the LPA there will need to be remedial measures agreed and included in an amended management plan. And where progress is not satisfactory there may need to be enforcement action.     

Site visits by the LPA to land delivering Significant On-site and Off-site Biodiversity Net Gain will be required. To cover the long-term costs for this Monitoring and Reporting Body role there will be a charge made by the LPA.      

Overseeing implementation of Biodiversity Net Gain across Leeds by different delivery organisations (residents committees, landowners, developers and a range of habitat banks and brokers) to a consistent level should help gain public trust in this new concept of Biodiversity Net Gain.     

What are the charges for the Monitoring and Reporting Body role and how is the payment made?

Significant On-site Biodiversity Net Gain:     

  • Up to 10 Biodiversity Units = £3 000
  • 10 up to 20 Biodiversity Units = £5 000
  • 20 and over Biodiversity Units = bespoke cost

Any Off-site Biodiversity Net Gain: 

  • Up to 10 Biodiversity Units = £3 000
  • 10 up to 20 Biodiversity Units = £5 000
  • 20 and over Biodiversity Units = bespoke cost

The above costs will apply until April 2025 and subsequently be index-linked annually to inflation.     

The above charges apply equally whether the Biodiversity Net Gain is delivered by a habitat bank, the developer, or other landowner with a legal interest in the land.     

The LPA will use the s106 mechanism for this charge. Where Significant On-site Biodiversity Net Gain and some Off-site Biodiversity Net Gain is also being proposed there will need to be two charges for the Monitoring and Reporting Body sum to reflect the need to monitor different parcels of land and carry out site visits to different locations (if more than one geographically located piece of land is being used for Off-site Biodiversity Net Gain there may need to be additional separate charges accordingly).       

The above charges are to cover the full 30-year period of time applicable for Biodiversity Net Gain to be delivered. These costs will be reviewed periodically to ensure they cover the full long-term costs associated with providing this role.     

What if we have designed the On-site development layout in line with the Biodiversity Gain Hierarchy but still need an Off-site solution?

The LPA wants to encourage high quality biodiversity enhancements On-site and will scrutinise applications that do not appear to have sufficiently demonstrated this through the input of a competent and experienced ecological consultant at the design stage of the layout. However, it is acknowledged that there will be times where 10% Biodiversity Net Gain cannot be delivered On-site.     

It should be noted that by designing the On-site layout through input of an ecological consultant there should be a smaller requirement for compensation Off-site.     

Where the LPA is satisfied that enough consideration has been made to retain any habitats of Medium (or higher) Distinctiveness, or it is simply not feasible to achieve the minimum 10% Biodiversity Net Gain On-site, then an Off-site solution may be considered as per the following options:     

  • through a habitat bank
  • on other land owned by the developer/applicant
  • on other land which the developer has a legal interest in

If none of the options above are available then National Statutory Biodiversity Credits will need to be purchased from Natural England.     

Will the Council be operating as a Habitat Bank?

The Council’s Executive on 7 February 2024 approved the setting up of a Habitat Bank Vehicle so that the Council can sell Biodiversity Units to developers to be delivered on its own land. Once this vehicle is set up developers will be able to consider using it as an option alongside other habitat banks operating in Leeds.       

How will Off-site Biodiversity Net Gain delivery be secured?

In all the scenarios above there will need to be a s106 with the LPA to ensure the Monitoring and Reporting Body role will be fulfilled – the s106 will need to be worded to ensure the management plan, progress reports and habitat monitoring are approved and submitted at suitable timescales.      

It is acknowledged that the applicant or developer may have purchased Biodiversity Units from a habitat bank and aims to secure these through a Conservation Covenant (to register the land on the Natural England National Sites Register) but a s106 will also be required for the LPA to fulfil its Monitoring and Reporting Body role.      

Can Off-site Biodiversity Net Gain be located anywhere within or outside of Leeds?

The LPA has an emerging Local Plan policy for Biodiversity Net Gain and this makes it clear which parts of Leeds should be seen as the priority areas for delivering any Off-site Biodiversity Net Gain. The justification for the following Strategic Significance priorities is based on the “Making Space for Nature” Lawton Review 2010 and the emerging West Yorkshire Local Nature Recovery Strategy.      

Strategic Significance scores for Off-site land should be scored as follows:     

  • High = within or immediately adjacent to any Nature Conservation Designations (Sites of Special Scientific Importance, Local Wildlife Sites, Local Geological Sites, or Local Nature Reserves) or Habitat of Principal Importance
  • Medium = within or immediately adjacent to the Leeds Habitat Network
  • Low = outside of the Leeds Habitat Network but in a location that forms a new strategic connection between two separate parts of the Network. Or anywhere else in the district with full public access.

It is important that the LPA can fulfil its function as the Monitoring and Reporting body and take enforcement action as a last resort where necessary. If Off-site parcels of land are being proposed outside of the Leeds district (apart from National Statutory Biodiversity Credits) consideration needs to be given to whether a s106 can be put in place to allow enforcement action to be taken by the LPA.      

Watercourse Biodiversity Units may be delivered outside the District provided they are in the same Management Catchment area but will need to be scored as Low Strategic Significance.      

Can the Blue-line land be classed as On-site for Biodiversity Net Gain?

No, only land in the Red-line for planning application purposes can be classed as On-site. Any Blue-line land parcels need to be inputted in the Metric as Off-site, and implementation covered by a s106 and entered onto the Natural England National Sites Register.     

When do we have to submit details for the national Biodiversity Gain Plan condition?

All consented planning applications which mandatory Biodiversity Net Gain applies to will have a nationally imposed condition that will need to be formally discharged prior to commencement of development (as per wording in the Decision Notice). There is a national Biodiversity Gain Plan template that must be used and approved by the LPA – and it cannot be submitted until at least a day after notification of permission.      

Provided you have followed the guidance on this webpage it should be straight-forward to fill in the Gain Plan and the LPA will already have considered much of the required information in order to allow a timely decision that the Gain Plan is satisfactory.     

Note that the Gain Plan requires a Biodiversity Gain Site Register Reference Number for any Off-site land proposed to be delivering Biodiversity Units.     

If Statutory Biodiversity Credits have been agreed as an acceptable Off-site solution by the LPA there will need to be proof of purchase provided.     

If the Gain Plan is incomplete or further relevant information is required, the condition discharge application may be refused – in which case you will need to submit another condition discharge application.     

Do we need to provide any general biodiversity enhancements in addition to Biodiversity Net Gain?

Biodiversity Net Gain only relates to habitats so does not provide specific enhancements for species. The emerging Local Plan has a policy for species enhancements, so these need consideration in addition to Biodiversity Net Gain. One example is the provision of integral bat roosting features and integral bird nesting features as per paragraph 023 of the NPPF Planning Practice Guidance. In Leeds these should be provided at a building ratio of at least 1:2 (at least 50% of existing and/or new built structures should have either an integral bat roosting or integral Swift nesting feature).