Biodiversity Net Gain: A Guide for Landowners

Key points

In England, most planning applications must deliver at least a 10% biodiversity net gain, measured with the statutory biodiversity metric.
From 6 August 2026, new applications on sites of 0.2 hectares or less are exempt unless priority habitat on the site would be affected.
Gains can be made on site, through off-site biodiversity units, or as a last resort through statutory credits bought from the government.
Landowners can sell off-site units from registered gain sites, but the habitat must be secured and managed for at least 30 years.
Wales, Scotland and Northern Ireland do not use England's mandatory 10% rule and rely on their own planning policies on biodiversity.

What is biodiversity net gain?

Biodiversity net gain (BNG) is a planning requirement in England that most new developments leave wildlife habitat in a measurably better state than before. Developers must show a gain of at least 10% using the statutory biodiversity metric, and secure new or improved habitat for at least 30 years. It has been mandatory since February 2024.

The requirement comes from the Environment Act 2021, which amended the Town and Country Planning Act 1990. The metric scores habitat by type, size, condition and location. An ecologist first surveys what is on the site now, known as the baseline, and the developer then shows how the scheme will exceed it. Councils can ask for more than 10% through local policy.

BNG applies in England only. Wales, Scotland and Northern Ireland handle biodiversity through their own planning policies, which we cover further down this guide.

Which sites are exempt, and what changed in August 2026?

New exemptions came into force on 6 August 2026 for planning applications made on or after that date. Applications submitted before then stay under the earlier rules. GOV.UK guidance says mandatory BNG does not apply to:

Small sites: developments where the site area within the red line boundary is 0.2 hectares or less.
De minimis impacts: developments affecting less than 25 square metres of on-site habitat or 5 metres of linear habitat such as hedgerow.
Temporary development: where the whole development is temporary and permission is for five years or less.
Householder applications: such as extensions and loft conversions.
Permitted development and certain other categories listed in the guidance.

The small-site, de minimis and temporary exemptions do not apply where priority habitat on the site would be affected. At the same time, the self-build and custom build exemption was removed for new applications, and minor developments that are not exempt can now go straight to off-site gains.

The government has also consulted on a targeted exemption for some residential brownfield development. That consultation closed in June 2026, and the government said it would respond in due course. If you are relying on an exemption, check the current guidance with a planning consultant, because the rules are still changing.

How does BNG affect what my land is worth?

BNG is a development cost, so it is one of the things a buyer allows for when working out what it can pay for land. It tends to affect value in three ways:

Space: habitat created on site takes land that might otherwise hold homes or gardens.
Cost: buying off-site units or statutory credits adds to the development budget.
Baseline: land with richer habitat, such as species-rich grassland, ponds or established hedgerows, needs more effort to exceed.

Clearing or damaging habitat before an application does not help. Planning practice guidance says that where habitat has been degraded without authorisation since 30 January 2020, the earlier, higher value should be used as the baseline. Our guide to how development land is valued explains where BNG sits among the other costs a developer deducts.

What order must developers follow to deliver the gain?

The rules set out a biodiversity gain hierarchy. Developers should first avoid or reduce harm through site choice and layout. They must then deliver gains in this order:

Habitat created or enhanced on the development site.
A mix of on-site gains and off-site units, either on land the developer controls or bought from someone else.
Statutory biodiversity credits bought from the government, as a last resort.

Significant on-site gains and all off-site gains must be maintained for at least 30 years. They are usually secured through a planning obligation with the council or a conservation covenant with a responsible body.

What are off-site biodiversity units, and could I sell them?

Off-site units come from creating or improving habitat on land outside the development site. A landowner can create units on their own land and sell them to developers who cannot meet the full gain on site. Some landowners work with a habitat bank operator, which creates and manages habitat on a larger scale and may help find buyers.

GOV.UK guidance says that before land can supply units you will need:

a baseline survey and metric calculation by a qualified ecologist
a legal agreement securing the habitat for at least 30 years
a habitat management and monitoring plan agreed with the council or responsible body
registration of the land on the biodiversity gain sites register, run by Natural England

Defra and Natural England do not set unit prices, and the register is not a marketplace, so there is no guarantee of a buyer. A 30-year commitment can affect how you farm, let, mortgage or pass on the land, and it may interact with other environmental payments. Speak to a land agent, solicitor and accountant before you commit. On larger holdings, such as farmland and paddocks, habitat creation and new homes can sometimes sit side by side.

How do Wales, Scotland and Northern Ireland approach biodiversity?

Nation	Approach
Wales	Planning Policy Wales expects development to deliver a net benefit for biodiversity through a step-wise approach: avoid harm first, then minimise and mitigate, with compensation as a last resort. Councils ask for a proportionate green infrastructure statement with applications. There is no mandatory 10% metric.
Scotland	National Planning Framework 4 (NPF4) Policy 3 says national and major developments, and those needing environmental impact assessment, must conserve, restore and enhance biodiversity, with significant enhancement on top of any mitigation. NatureScot is consulting on a Scottish biodiversity metric until 30 November 2026, with the full metric expected in 2027.
Northern Ireland	There is no mandatory biodiversity net gain rule at the time of writing. Public bodies have a duty to further the conservation of biodiversity, and the Department of Agriculture, Environment and Rural Affairs (DAERA) consulted in 2026 on a draft Nature Recovery Strategy, which signalled that a net gain approach for planning could be explored.

In all three nations, ecology surveys and habitat proposals are still a normal part of most housing applications, even without England's numerical target.

How does Land to Homes deal with biodiversity on a site?

Our free site appraisal includes a first look at habitat, hedgerows, watercourses and designations, so you know early whether BNG or local biodiversity policy is likely to shape the layout. If we promote your land through a promotion agreement, there is nothing to pay up front: we fund the planning work, including ecology surveys and the biodiversity metric, and those costs are recovered from the sale proceeds only if the land sells with planning. Find out more about the planning stage on our planning permission page, or start with the free appraisal tool.

Frequently asked questions

Does biodiversity net gain apply to a small garden plot?

In England, a planning application made on or after 6 August 2026 for a site of 0.2 hectares or less, measured by the red line boundary, is usually exempt unless priority habitat on the site would be affected. Applications made before that date follow the earlier rules. Wales, Scotland and Northern Ireland do not use England's BNG rules, but their own biodiversity policies still apply, so check with the council or a planning consultant.

Should I clear scrub or hedges before selling my land?

Generally not. In England, planning guidance says that where habitat has been degraded without authorisation since 30 January 2020, the earlier, higher biodiversity value is used as the baseline, so clearance can make the requirement harder to meet. Wildlife laws protecting nesting birds and other species also apply across the UK. Talk to an ecologist and your planning adviser before doing any work on land you plan to sell.

How long must off-site habitat be managed?

At least 30 years from when the habitat enhancement works are completed, as set out in the legal agreement. That agreement is usually a planning obligation with the council or a conservation covenant with a responsible body. The landowner is responsible for creating the habitat, managing it, monitoring it and reporting on it, so weigh the long-term cost and commitment carefully before you sign anything.

Can biodiversity net gain stop my land getting planning permission?

On its own, rarely, because most sites can meet the requirement through a mix of on-site habitat, off-site units and, as a last resort, statutory credits. It is more often a question of cost and layout. Sites with irreplaceable habitat, such as ancient woodland, face much stricter treatment. A good appraisal identifies these issues early, before money is spent on a full planning application.

Sources

This guide is general information about how land and housing processes usually work. It is not legal, tax or financial advice. Rules differ between England, Wales, Scotland and Northern Ireland and change over time, so take advice from a solicitor, accountant or land agent on your own situation.

Biodiversity net gain for landowners: what it means for your land