Biodiversity net gain
Biodiversity net gain is an approach in which development leaves biodiversity in a measurably better state than before, after accounting for losses and gains against a defined baseline. In England's statutory system, covered developments must generally deliver at least a 10% increase in biodiversity value using the prescribed metric and hierarchy.
In simple terms
Biodiversity net gain compares pre-development biodiversity value with the value expected after development, including qualifying on-site habitat, registered off-site gains, and statutory credits where permitted. England's system uses standardized biodiversity units and a gain hierarchy. Significant on-site and off-site habitat gains generally require long-term management. Applicability is legal and date-sensitive: exemptions and commencement rules differ, and separate rules for nationally significant infrastructure projects are scheduled to begin on 2 November 2026.
Why it matters
A measurable objective can make habitat losses, replacement plans, and long-term delivery more visible in development decisions. It does not make every impact interchangeable: irreplaceable habitats, location, ecological condition, time lags, and uncertainty require special treatment. A biodiversity offset can be one delivery mechanism, but it is not identical to the overall net-gain requirement. Readers should distinguish the broad approach from the exact statutory requirements applying to a particular project and date.
Example
For example, a covered English development calculates baseline habitat units with the statutory metric, first avoids and reduces damage, then plans qualifying on-site enhancement through suitable nature-based solutions. If a shortfall remains, it may allocate registered off-site units and, as a last option, statutory credits, subject to the rules in force.
How it differs
Biodiversity offset
Biodiversity net gain is the measured overall outcome sought after losses and gains are combined; a biodiversity offset is a last-resort measure for residual impacts after earlier mitigation steps.
References
Current status
- As of
- Issuer
- Government of the United Kingdom
- Jurisdiction
- England
- Instrument or version
- Schedule 7A to the Town and Country Planning Act 1990, as inserted by the Environment Act 2021
- Status
- Mandatory for covered development in England; exemptions and commencement dates vary by development type under current guidance.
Applicability: As of 2026-08-12, covered development generally has a 10% objective. Current guidance exempts applications for developments of 0.2 hectares or below from 6 August 2026 and schedules separate nationally significant infrastructure project rules from 2 November 2026.