where—

• Y is—

  1. a

     for a hereditament shown in a local list for 31st March 2023, the rateable value shown for the hereditament for that date in that list, and

  2. b

     for a hereditament shown in the central list for 31st March 2023, the rateable value shown for the hereditament for that date in the central list or the value certified by the appropriate valuation officer to be the rateable value which would have been shown in the central list for the hereditament for that date if that had been the only hereditament of the designated person shown in the central list for that date; and

• Z is the small business non-domestic rating multiplier for the financial year beginning on 1st April 2022.