61.—(1) For the purposes of regulation 60, A is calculated as follows.
(2) Where the tariff start date is within any tariff period commencing on 1st April, commencing with 1st April 2018, A is the relevant tariff which would have applied had the tariff start date fallen within the previous tariff period (“the previous tariff”), adjusted by the percentage increase or decrease in the consumer prices index for the calendar year ending with the 31st December immediately preceding the commencement of that tariff period, the resulting figure being rounded.
(3) Where the tariff start date is within any subsequent tariff period commencing with 1st July, 1st October or 1st January, commencing with 1st July 2018, A is the previous tariff.