Enter a legal agreement for biodiversity net gain
How land managers, developers, local planning authorities and responsible bodies can enter into a legal agreement for biodiversity net gain.
Applies to England
Biodiversity net gain (BNG) is mandatory from 12 February 2024.
A legal agreement is an obligation to enhance and maintain a habitat.
Your legal agreement for off-site gains or significant on-site gains must last for at least 30 years.
Who can enter into a legal agreement for BNG
Land managers
You can enter a legal agreement if you:
- are the landowner
- have a lease on the land that is at least the same length as the legal agreement
If your lease is shorter, you’ll need to include the freeholder in your legal agreement.
Your legal agreement will not replace any previous property rights.
Developers
If the off-site gain is secured with a legal agreement by the landowner, the developer does not need to enter a legal agreement.
If the developer is making:
- off-site gains on their own land that’s outside the development site, they must secure these gains with a legal agreement
- significant on-site gains, they need to enter a legal agreement as the landowner (the LPA might also need to be involved in this legal agreement)
LPAs and responsible bodies
LPAs and responsible bodies should:
- monitor the agreement to make sure the landowner meets their obligations
- register the planning obligation or conservation covenant with the local land charges register
LPAs and responsible bodies should not enter into an agreement if they do not think the landowner will meet their obligations.
On-site gains
For significant on-site gains, developers must have a legal agreement or planning condition.
If developers use a planning condition, this is separate to the condition that requires them to achieve 10% BNG.
You will also need a legal agreement if on-site gains are not significant, but contribute to locally important species or ecological networks. Check with the local planning authority (LPA) if you’re not sure.
Your legal agreement for on-site gains must last for at least 30 years from the date you complete the development.
Off-site gains
To buy or sell off-site gains, you must have a legal agreement.
The legal agreement for off-site gains must last for at least 30 years from the date you finish the habitat enhancement.
How to enter a legal agreement
There are 2 types of legal agreement for BNG:
- planning obligation (section 106) with an LPA
- conservation covenant agreement with a responsible body
As part of the legal agreement, you (or a third party you have sub-contracted to) will need to commit to:
- creating or enhancing habitats
- managing the habitats for at least 30 years
The legal agreement must be in writing and signed by all parties (‘executed as a deed’).
You should get legal advice before entering a legal agreement. You will have to pay for any legal or other costs related to the agreement.
Planning obligation
A planning obligation agreement is between landowners and their LPA. The LPA will be responsible for enforcing the agreement.
Conservation covenant agreement
A conservation covenant agreement is between landowners and a responsible body. This type of legal agreement gives you more flexibility over who the agreement is with.
There is a list of responsible bodies.
How long your legal agreement must last
The legal agreement starts from the date you sign it.
For on-site BNG, the 30-year maintenance period starts when you complete the development.
For off-site BNG, the habitat enhancement may not start right away. The 30-year maintenance period starts when you complete all the habitat enhancement works needed on that land under the legal agreement. That could mean the whole of the gain site, or part of the gain site.
Habitat enhancement works
Habitat enhancement works means capital works such as:
- planting trees
- digging ponds
- fencing
- sowing wildflower seeds
It can also mean stopping management activities that could prevent the proposed habitat enhancement from happening. For example, it could mean:
- stopping applying fertiliser to grassland
- changing a grazing regime
- stopping ditch clearing
Completion of habitat enhancement works can also mean just stopping management activities with no capital works.
Your legal agreement must state clearly when the habitat enhancement work will be completed.
Landowners must maintain the enhanced habitat for at least the length of your agreement.
What to include in your legal agreement
You’ll need to provide detailed information on your planned biodiversity habitat enhancements for the site (for example, create 2 hectares of neutral grassland in moderate condition).
You may also include what specific actions you’ll take to achieve the habitat enhancements (for example, sow a seed mix or carry out bi-annual cuts).
You’ll also need to agree who is responsible for:
- creating or enhancing the habitats
- maintaining the habitats
- monitoring the habitats
You can sub-contract the habitat work to a third party, but the legal agreement sets out who is responsible. You cannot include a subcontractor in the legal agreement. Only the landowner, LPA or responsible body can be responsible.
You can provide a detailed schedule of management and monitoring in a habitat management and monitoring plan (HMMP).
You can view example legal agreements from the Planning Advisory Service.
How you’ll allocate habitat enhancements
You’ll need to:
- agree how you’ll allocate the enhancements (for example, to one or more developments)
- decide who will agree the allocation
Find out how to record the allocation of off-site units.
Habitat location
You’ll need to identify the land where you’ll be creating or enhancing the habitat.
What you’ll need to agree with the LPA or responsible body
You’ll need to agree:
- how you’ll monitor the biodiversity gain site, including a schedule and how to access the land
- an end date that is at least 30 years from when you complete creating or enhancing the habitat
- any consent or licences that you need
- what actions the LPA or responsible body can take if you do not meet your obligations
- what actions you will take if the habitat enhancement does not go as planned
- how you will make permitted changes or manage disputes
- any funding arrangements (for example, for ongoing monitoring) and a payment schedule
- the biodiversity value of the pre-enhancement habitat (calculated using the statutory biodiversity metric)
If the habitat or enhancement is within the wildlife consultation area of an aerodrome, you must agree that it does not harm aircraft operations.
You’ll need to agree that the relevant aerodrome:
- was notified of the proposed agreement
- had the opportunity to assess for potential hazards to aircraft operations
- is satisfied with the risk to aviation safety
What happens if you do not meet the terms of the legal agreement
If you do not maintain the biodiversity gains in your legal agreement, the appropriate body may take enforcement action.
If you have secured your on-site or off-site gains with a:
- planning condition or planning obligation, the LPA may take enforcement action
- conservation covenant, the responsible body may take enforcement action
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Updates to this page
Last updated 4 October 2024 + show all updates
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Added clarification that ‘enhancement works’ can include stopping normal maintenance works as well as, or instead of, positive actions to enhance habitat.
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Updated to add a link to the list of responsible bodies.
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Updated box at top of page to state that biodiversity net gain (BNG) is mandatory from 12 February 2024 and removed the 'draft guidance' label. Changed 'secure' to 'enter into', provided clarity on what a legal agreement is, as well as more information around when the legal agreement starts.
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Added information about aerodrome safety.
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First published.