The BNG rules are not based on Local Planning Authorities or counties but on National Character Areas.

There are 159 National Character Areas (NCAs) in England.

The rules contain a number of incentives. 

If a BNG net gain of at least 10% cannot be achieved on site the government’s BNG Credit pricing is designed to encourage acquisition of BNG Units from the open market.

To incentivise the use of Government BNG Credits as a last resort a BNG Credit is worth 0.5 of a BNG Unit, so two BNG Credits are required for one BNG Unit.

To encourage local nature recovery use of local BNG Units is incentivised;

• within the same NCA BNG Units are worth one Unit value
• BNG Units in an adjacent NCA are worth 0.75 of a Unit value
• BNG Units elsewhere are worth 0.5 of a Unit value.

This means that depending on the site and BNG Unit location it may be necessary to acquire 1, x 1.33 or x 2 BNG Units for each one required.