13. Where either–
(a)the business of making cider is discontinued at cider premises having cider therein; or
(b)a certificate of registration held under regulation 6 above in respect of premises having cider therein is surrendered or cancelled; or
(c)any cider is found to be deficient or missing from cider premises and the maker is unable to account for the deficiency to the Commissioners' satisfaction,
the duty on the cider shall be charged at the time of discontinuance or at the time of the surrender or cancellation of the certificate of registration or at the time the deficiency occurred, as the case may be, and at the rate in force at that time; and the duty shall be paid in accordance with regulation 23(2) below.
Provided that where the time that any deficiency occurred cannot be established to the Commissioners' satisfaction, the rate of duty shall be taken to be the highest rate in force between the time of the latest stocktaking made under regulation 20 below before the discovery of the deficiency and the time of that discovery.