Biodiversity Net Gain for landowners: how habitat and BNG units can pay

For most of the past century, the value in a field was measured in what you could grow on it or build on it. There is now a third thing it can be worth: the nature it holds, and the nature you can add to it. Since Biodiversity Net Gain became a legal requirement, most new development in England has had to leave the natural world measurably better off than it found it, and a market has grown up to make that happen. Landowners sit on the supply side of that market. It is worth understanding what is being traded, and being honest about the length of the commitment it asks of you.

This is a plain-English explanation, not legal or financial advice, and the rules are still moving. Treat it as the shape of the thing and check the current position for your own land.

What Biodiversity Net Gain actually requires

The principle is simple. Most planning permissions must now deliver at least a 10% net gain in biodiversity, meaning the site ends up richer in nature after development than before. The measuring is done through a government metric that turns habitats into a common currency of “biodiversity units”, scored by the type of habitat, its condition, its size and where it sits.

A developer is expected to achieve that gain on the site itself first. But many cannot, because there is only so much you can do with a compact housing scheme. Where they fall short, they are allowed to buy the difference in the form of off-site biodiversity units. That is where a landowner comes in. If you take land and enhance its habitat, turning a low-scoring arable field into species-rich grassland, wetland or woodland, you create units that a developer elsewhere can buy to meet their obligation.

The work rests on two numbers. First, a baseline: an ecologist surveys what your land holds today and scores it. Then the uplift: the difference between that baseline and the richer habitat you commit to creating and maintaining. The gap between the two, secured properly, is what has value. The professional body CIEEM, which represents ecologists, has been clear that the quality of that baseline survey matters enormously, because everything downstream is built on it.

The catch is thirty years long

This is the part that deserves emphasis rather than a footnote. Habitat created for BNG must be secured and maintained for at least thirty years, and that is no figure of speech. It is a legal commitment, usually locked in through a planning obligation or a conservation covenant, that runs with the land and binds you and whoever comes after you.

Thirty years is a long time to give up your options on a parcel of ground. The Country Land and Business Association, the CLA, and rural advisers such as Strutt & Parker have both pointed to this as the central decision a landowner has to weigh: the income can be real, but it is earned slowly and it ties the land down for a generation. Land committed to habitat is land you cannot easily develop or sell for another use, nor return to intensive farming. You are also taking on the responsibility, and the cost, of managing that habitat to a standard for three decades, not just planting it and walking away.

This is why habitat banks have emerged. Rather than a single small deal, a landowner sets aside a larger area, creates habitat at scale, and sells units from it to multiple developers over time. It can make the economics and the management more sensible. It also, of course, commits more of your holding for longer.

Two changes worth watching, and one thing it is not

The rules are being tightened in ways that affect where and how units are worth creating. From July 2026, Defra has been aligning BNG delivery more closely with Local Nature Recovery Strategies, the regional plans that identify where nature recovery would do the most good. In plain terms, where you create habitat is starting to matter, not only how much. Habitat made in a priority area, in line with the local strategy, is likely to be worth more than the same habitat made somewhere the strategy does not point to. Defra set out this direction on its Environment blog in April 2026.

Then, from November 2026, BNG requirements extend to Nationally Significant Infrastructure Projects, the large road, rail and energy schemes that have so far sat outside the regime. That widens the pool of buyers who will need units, which matters for anyone thinking about supply over the long horizon these commitments demand.

One clarification, because the two are easily confused. BNG sits alongside, and is separate from, the Nature Restoration Fund. The Fund is a different government mechanism for dealing with certain environmental impacts through a pooled payment. BNG is its own obligation with its own units and its own thirty-year duty. Do not assume one satisfies the other.

Where it fits in a whole-holding view

We think about land as a whole rather than a single field with a single fate, and BNG is a good illustration of why. A parcel that scores poorly for development, an awkward corner or a wet field that would never carry houses well, may be exactly the piece that creates the most biodiversity uplift and therefore the most value as habitat. Meanwhile the land with real development potential is usually better kept for that. The skill is in reading the whole holding and deciding which ground does which job, rather than pledging a promising field to thirty years of grassland because a unit price looked good in isolation.

BNG is one option among several, and the stacking rules, which govern whether a single piece of land can earn from more than one nature scheme at once, are intricate and still settling. That complexity, together with the length of the commitment, is why this is a decision to weigh slowly and with proper advice, not to rush.

If you want a first read on what your land might be capable of, across development potential and nature markets alike, our free Land Potential Check is an honest place to start. It is an indication drawn from open data, never a valuation. The real answer for any specific holding comes from walking the ground and doing the work, and from being straight about what thirty years asks of you.