168.New section 52ZF sets out what a billing authority must do if it sets an excessive council tax increase. It must make substitute calculations which will have effect, in the event that the authority’s proposed excessive increase in council tax is rejected in a referendum or the authority fails to hold a referendum when it is required to do so. The amount calculated as an authority’s relevant basic amount of council tax in the substitute calculations must be below the amount which is considered excessive under the principles.