If the Secretary of State decides under section 100 above to designate an authority he shall notify it in writing of—
A designation—
Where a charging authority has been designated under this section, and after the designation is made the authority makes substitute calculations in relation to the year in accordance with section 95 above, the substitute calculations shall be invalid unless they are made under section 107(1) below.
Where a precepting authority has been designated under this section, and after the designation is made the authority issues any substitute precept for the year, the substitute precept shall be invalid unless it is issued under section 107(2) below.
Before the end of the period of 28 days beginning with the day it receives a notification under this section, an authority may inform the Secretary of State by notice in writing that—
References in the following provisions of this Part to a designated authority are to an authority designated under this section.