74.—(1) A person who has made a claim may amend it at any time before a determination has been made on it, by a notice in writing delivered or sent to the designated office and any claim so amended shall be treated as if it had been amended in the first instance.
(2) A person who has made a claim may withdraw it at any time before a determination has been made on it, by notice to the designated office, and any such notice of withdrawal shall have effect when it is received.