Securing biodiversity gain for thirty years

Securing biodiversity net gain for thirty years is a land management obligation dressed as a planning condition, and it is the part of the regime developers underestimate. The metric calculation takes weeks. The securing arrangement outlives the development, the sales programme, probably the planning consultant and possibly the company, and it has to survive the land changing hands more than once. Schedule 7A to the Town and Country Planning Act 1990 requires significant on-site enhancement to be maintained for at least thirty years after the development is completed, and off-site gains to be secured for the same period.

Two legal instruments can do that work, and they behave differently.

Why thirty years changes the legal structure

A planning condition cannot carry a thirty-year management obligation on its own, because conditions do not bind successors in the way a land obligation does and they are poorly suited to requiring positive action over decades.

So the regime reaches for instruments that run with the land. A planning obligation under section 106 of the 1990 Act, or a conservation covenant under Part 7 of the Environment Act 2021. Both bind successors in title. Both are registrable. Both need somebody willing and able to enforce them in year 27.

That last point is the one to think about first. Thirty years is long enough for a management company to be struck off, a council's monitoring team to be restructured twice, a responsible body to cease operating and a parcel of amenity land to be sold to a party who has never heard of the gain plan. Design the arrangement for that, not for the day of completion.

The biodiversity gain condition is deemed to be attached to almost every planning permission, as set out in the biodiversity gain condition on every permission, and the gain plan has to be approved before development begins.

Section 106 agreements as the securing mechanism

For most schemes with on-site gain this is the default, mainly because the parties are already negotiating an agreement and the council is already the enforcing body.

What the obligation needs to contain: the land to which it applies, defined by plan and by title number. The habitats to be created or improved and their target conditions. The habitat management and monitoring plan, either appended or submitted for approval under the agreement. The management period, expressed as thirty years from a defined trigger. Reporting obligations with dates. A remedial mechanism if monitoring shows the targets are not being met. And the funding arrangement.

One structural weakness is worth naming. Section 106A allows a party to apply to modify or discharge an obligation after five years, with a right of appeal to the Secretary of State if the authority refuses. A thirty-year obligation sits awkwardly with a five-year modification right, and councils respond by drafting the biodiversity provisions tightly and by resisting modification. Whether that holds over three decades is untested, and anyone saying otherwise is guessing.

The practical advantage of section 106 is that the council is the enforcer and the obligation shows as a local land charge, so a buyer's solicitor will find it.

Conservation covenants and responsible bodies

A conservation covenant is an agreement between a landowner with a qualifying estate and a responsible body designated by the Secretary of State, executed as a deed and stating on its face that it is a conservation covenant agreement. It binds successors in title and the responsible body enforces it.

Where it earns its place is off-site delivery. A habitat bank, a farm selling units, or a parcel of land unconnected to the development is often better handled through a covenant with a body whose purpose is conservation than through an agreement with a planning authority that has no interest in the land.

The questions to ask before choosing it:

1. Who is the responsible body, what is its designation, and what happens to the covenant if it ceases to be designated or ceases to exist.
2. What is it being paid, over what period, and is that payment front-loaded or spread.
3. What are its enforcement powers under the agreement, and has it enforced anything before.
4. How is the covenant disclosed on a sale of the land, and will a buyer's search pick it up.

For off-site units the land also has to be entered on the biodiversity gain site register and the units allocated to the specific development, and the registration and the securing instrument have to describe the same land and the same habitats. A mismatch between the register entry and the covenant is a defect that surfaces at gain plan approval.

What a habitat management and monitoring plan must cover

The plan is the operative document for thirty years, and it gets written in a hurry at the end of an application. That is the wrong order.

Monitoring is normally more frequent in the establishment years and periodic thereafter, with the schedule set in the plan and agreed with the authority. Set the survey windows by season rather than by calendar date, because botanical condition assessment is only meaningful through the growing season.

Write the prescriptions for a grounds maintenance contractor rather than for an ecologist. A plan that says manage the grassland to maintain species-rich condition will be read as mow it, and a plan that says cut once after mid-July, remove arisings, no fertiliser, no herbicide except spot treatment of injurious weeds will not. The practical overlap with the soft landscape works means the Landscape Strategy and the management plan should be written by people who have read each other's documents.

Funding the management period

Thirty years of management costs money at a point when the development has been sold and the developer has gone.

The mechanisms in use: a capital sum paid to the council or the responsible body at a defined trigger, often before occupation. A bond or guarantee. A charge on the land. A service charge through a management company, for residential schemes with communal land. Or a commuted sum to a third party that takes on the land and the obligation.

Three things to get right in the appraisal. The cost has to be modelled over thirty years with an allowance for cost inflation, not as a single present-day figure. The authority's own monitoring fee is separate from the management cost and is also payable over the period. And the trigger for payment matters to cash flow, so negotiate it alongside the other obligation triggers rather than accepting the first draft.

Where a management company carries the obligation, a developer's exposure does not end at handover unless the agreement says so. Read the step-in provisions carefully.

Monitoring reports and who receives them

The reports are the evidence that the obligation is being met, and the commonest failure is simply not sending them.

Each report should state the survey date and surveyor, the habitat condition assessed against the same criteria as the baseline, the metric position if units are being tracked, what management was carried out since the last report, where targets are not being met and why, and the remedial action proposed. It goes to the authority under a section 106 agreement, or to the responsible body under a covenant, by the deadline in the instrument.

Councils vary in how actively they chase reports, and a developer or management company that stops reporting is in breach whether or not anyone notices. The habitats are also not always the problem: a habitat failing because of drought or disease is a different conversation from one failing because nobody mowed, and the reports are what distinguishes them. Where the site contains habitat that cannot be recreated at all, the regime takes a different route entirely, covered in irreplaceable habitats and the biodiversity gain exception.

What happens when land changes hands

Both instruments bind successors, which is the point of using them, and the practical work is in disclosure and in who actually does the management.

For a sale of a development plot, the obligation appears in the local land charges register for a section 106 and should be disclosed in the contract. For a covenant, check how it is registered and whether a standard search finds it. For land transferred to a management company or a parish council, the transfer needs to carry the obligation expressly and the recipient needs the funding alongside it, because a body that inherits a thirty-year duty without a budget will not perform it.

Keep the gain plan, the metric file, the management plan and the securing instrument together as one bundle, and hand that bundle over at every transfer. A Biodiversity Net Gain Assessment must be completed by a competent person under the Environment Act 2021 regime, and PlanScope's draft is a starting point for that professional rather than a substitute. For specialist technical reports, qualified professional input may be required.

Source instruments are Schedule 7A to the Town and Country Planning Act 1990, inserted by the Environment Act 2021, and Part 7 of the Environment Act 2021 for conservation covenants. Position stated as at 8 October 2026, and the planning law updates timeline is where to follow changes. This is general guidance, not legal advice; take legal advice on the securing instrument before committing to a mechanism.