Biodiversity net gain: the 10% requirement, step by step

Biodiversity net gain (BNG) is a condition attached to most planning permissions in England. The biodiversity value attributable to a development must exceed the pre-development value of the site by at least 10%, measured with the statutory biodiversity metric. Development may not begin until the planning authority has approved a biodiversity gain plan showing how that will be met.

Four things: a 10% gain over the site baseline, measured separately for area habitat, hedgerow and watercourse units; delivery through the statutory hierarchy of on-site habitat first, then registered off-site units, then statutory credits as a last resort; an approved biodiversity gain plan before commencement; and maintenance of significant on-site gains and all off-site gains for at least 30 years.

For all planning applications under Part 3 of the Town and Country Planning Act 1990, major and minor, on 12 February 2024. Minor development was temporarily exempt for applications made before 2 April 2024, which is why that date is often quoted, but it was never a separate commencement. Crown development came into scope on 1 May 2025, and for Nationally Significant Infrastructure Projects the requirement applies to development consent applications made on or after 2 November 2026.

Start with a habitat baseline survey by a competent person, such as an ecologist, before the layout is fixed. Run the statutory metric on the baseline and on the proposed scheme, then design the gain through the hierarchy: on-site habitat first, registered off-site units next, statutory credits last. After planning permission is granted, submit a biodiversity gain plan on the government template with the metric, pre- and post-development habitat plans and any off-site or credit evidence. The planning authority has eight weeks to decide, and work cannot start until it approves.

For new applications: householder applications, de minimis development, the High Speed Rail network, biodiversity gain sites serving another development, and, from 6 August 2026, sites of 0.2 hectares or less and wholly temporary development of up to five years where no on-site priority habitat is affected. The self-build exemption was removed for applications made on or after 6 August 2026.

Use registered off-site units, bought from a biodiversity gain site on Natural England's register or created on your own land and registered. Only if that is not possible may you buy statutory biodiversity credits from the government. Credits are priced from £42,000 to £650,000 each, and you need two credits for every unit you are short.

At least 30 years. For significant on-site gains, the habitat must be maintained for at least 30 years after the development is completed, secured by a planning condition, a section 106 planning obligation or a conservation covenant. Off-site gains are secured the same way, for at least 30 years from completion of the habitat works.

No. The Schedule 7A condition applies to planning permission in England. Wales, Scotland and Northern Ireland have their own planning systems.

The only prices the government publishes are for statutory biodiversity credits, the last-resort option, from £42,000 to £650,000 per credit as at 2 June 2026, with no VAT. Defra and Natural England do not set off-site unit prices, which are agreed between buyer and seller, and ecological survey costs depend on the site. This page gives no market range for either.