Nutrient mitigation contributions and how they are secured
A nutrient mitigation contribution has to be secured before the authority can conclude no adverse effect. That makes the section 106 the critical path, not the ecology.
A nutrient mitigation contribution is secured through a planning obligation, not a condition, because the mitigation almost always sits on land you do not control. The timing point is the one that governs the programme: regulations 63 and 64 of the Conservation of Habitats and Species Regulations 2017 require the competent authority to be satisfied, beyond reasonable scientific doubt, that the development will not adversely affect the integrity of the protected site before permission can be granted. Mitigation that is merely intended does not get you there. It has to be in place, or legally secured, at the point of decision.
That reverses the usual order of work. On most schemes the agreement follows the resolution. Here the credit purchase and the obligation have to be ready before the authority can resolve at all.
Why a contribution rather than on-site mitigation
On-site mitigation means taking land out of nutrient-generating use, or treating effluent to a standard that removes the net load. For a site of a few hectares in a catchment where the calculated nitrogen load is small, the arithmetic rarely works. You would need more land than the scheme has.
So most developers buy credits from a scheme that has already created the mitigation, usually by converting agricultural land to a low-nutrient use such as woodland or species-rich grassland, or by funding a wetland.
On-site remains worth testing in two cases. Where the site includes existing agricultural land whose current nutrient load can be counted as a baseline credit against the new load. And where the scheme is large enough to fund its own wetland, which changes the economics and gives you control of the delivery risk.
Credit schemes and who operates them
Three kinds of provider exist in practice. Natural England operates a nutrient mitigation scheme and sells credits in some catchments. Local planning authorities and groups of authorities have set up their own schemes, often using land they already own. And private providers create habitat banks and sell credits directly.
Each has a different contractual shape, and the diligence questions are the same across all three.
- Is the mitigation already delivered, or is it a promise with a delivery programme attached?
- What legal mechanism holds the land in its mitigated state, and for how long?
- Has Natural England accepted the scheme's methodology for the catchment in question?
- Does the authority determining your application accept credits from that provider, in writing?
- What happens to your credits if the provider becomes insolvent?
That last question is the one most often skipped, and it is the one that turns into a problem years later.
Securing in perpetuity through an obligation
The obligation has to do three things: identify the credits, prevent occupation until they are secured, and prevent the land that generates them from reverting.
A workable structure ties occupation of the dwellings to delivery. A clause preventing occupation of any dwelling until the council has confirmed in writing that the mitigation has been secured gives the authority an enforceable hook, and gives you flexibility on when in the build programme the purchase completes.
Where the mitigation land is owned by a third party, that party normally needs to be a signatory, or there needs to be a separate agreement over the mitigation land to which your obligation refers. A unilateral undertaking is sometimes used where the council will not engage, though it is weaker for this purpose because it cannot bind the mitigation landowner.
Natural England's advice expects mitigation to be secured for the lifetime of the development, and the period written into these agreements runs to many decades. The exact figure differs between catchments and between advice notes, so take it from the advice applying to your site rather than from a precedent agreement for somewhere else.
Our note on nutrient neutrality credits and the section 106 goes into the drafting in more detail, and the broader question of which instrument secures what is covered in section 278, section 38 and section 106.
Timing against the appropriate assessment
Sequence it like this.
- Establish whether the site is in a catchment where Natural England has issued advice, and which protected site is affected.
- Calculate the nutrient budget using the methodology for that catchment, with a suitably qualified ecologist. Councils expect a qualified author for ecology work, and professional review is strongly advised.
- Identify a provider and reserve credits, with a reservation period that covers the determination period plus an extension.
- Agree the obligation wording with the authority's legal team in parallel with the officer's assessment.
- Let the authority complete its appropriate assessment on the basis of the secured mitigation.
- Complete the agreement, then the permission issues.
The reservation period in step three is where money is lost. Reserve for too short a period and you pay twice when determination slips. Reserve for too long and you have paid for an option you may not need. Twelve months with an extension right is a reasonable starting negotiation.
Where the application also needs foul drainage evidence because the treatment works has limited headroom, that work overlaps with the nutrient calculation and belongs in a Foul Sewage Assessment, ideally by the same consultant.
Pricing, indexation and refunds
Credit prices are quoted per kilogramme of total nitrogen per year, or as a capital sum for the whole mitigation requirement, and they vary by catchment and provider. Do not budget from a figure you read somewhere. Get quotes for your own catchment.
Three commercial terms deserve attention in the contract.
Indexation, because a credit reserved now and drawn down in three years will usually be priced at the index-linked figure rather than the quoted one. Refunds, because a scheme that is refused or withdrawn should release the credits, and not every provider offers that. And transferability, because a credit tied to a specific permission is worth less on a site sale than one that can be moved.
Risk if the mitigation scheme fails
The legal risk sits with the authority's conclusion, which is why authorities are careful. If the mitigation does not materialise, the appropriate assessment was wrong, and the permission is vulnerable.
For the developer the practical exposure is occupation. Where the obligation prevents occupation until mitigation is confirmed, a failed provider stops sales. The protections worth negotiating are a step-in right over the mitigation land, a substitution clause allowing credits from an alternative accepted provider, and evidence that the mitigation land is already legally secured rather than contracted to be.
Where a scheme is later varied, check whether the nutrient obligation carries across, because a section 73 permission is a new permission and the position is not automatic, as set out in do section 106 obligations carry over to a section 73 permission.
Proposals to replace site-by-site nutrient mitigation with a strategic fund have been brought forward in Parliament. Check whether the relevant provisions have been brought into force, and what transitional arrangements apply, before assuming any of it affects your application.
Evidence for the authority
What the case officer needs on file, in one place:
- The nutrient budget calculation, with the methodology version and the catchment advice it follows.
- A credit reservation or purchase confirmation naming the scheme and the quantum.
- Evidence of the legal mechanism securing the mitigation land, with the term stated.
- Confirmation that Natural England accepts the methodology and, where the authority asks for it, Natural England's response on your specific scheme.
- Draft obligation wording keyed to the above.
The obligation also has to satisfy regulation 122 of the Community Infrastructure Levy Regulations 2010, meaning necessary to make the development acceptable, directly related to it, and fairly and reasonably related in scale and kind. Nutrient mitigation passes those tests easily when the calculation is site-specific. It passes them less easily when an authority asks for a round-figure contribution to a general fund without showing the link, and that is worth pushing back on politely and in writing.
Baseline ecology work underpins all of it, so commission the Preliminary Ecological Appraisal early enough that the nutrient budget is not waiting on it.
PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. This is general guidance rather than legal advice, so check the position with your local planning authority or a qualified professional before relying on it.
Frequently asked questions
Can nutrient mitigation be secured by condition instead of a section 106?
Rarely, because the mitigation usually sits on land outside the applicant's control and a condition cannot require works on third party land. A planning obligation can bind the mitigation landowner, or refer to a separate agreement over that land. Some authorities accept a unilateral undertaking, though it cannot bind anyone other than the applicant.
When do the credits need to be in place?
Before the authority concludes its appropriate assessment, because regulations 63 and 64 of the Conservation of Habitats and Species Regulations 2017 require certainty of no adverse effect before permission is granted. In practice developers reserve credits during determination and complete the purchase when the agreement completes, with occupation tied to confirmation of delivery.
How long does nutrient mitigation have to be secured for?
For the lifetime of the development, which agreements express as a period of many decades. The exact figure varies between catchments and between the advice notes that apply to them, so take it from the Natural England advice for your catchment rather than from a precedent agreement drafted for a different protected site.
What happens if the credit provider becomes insolvent?
Your obligation still prevents occupation until mitigation is confirmed, so the commercial exposure falls on you. Negotiate a substitution clause allowing credits from an alternative provider the authority accepts, and prefer schemes where the mitigation land is already legally secured rather than contracted to be secured at a future date.
Does the contribution have to meet the section 106 statutory tests?
Yes. Regulation 122 of the Community Infrastructure Levy Regulations 2010 requires an obligation to be necessary to make the development acceptable, directly related to it and fairly and reasonably related in scale and kind. A site-specific nutrient budget satisfies that readily. A round-sum payment into a general fund with no calculation behind it does not.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.