(1) In this section -

‘relevant date’, in relation to a repayment, means -

(a) the date which is 93 days after the date on which a valid claim in respect of the repayment is made to the Commissioners, or

(b) if the repayment is due to a mistaken assumption in the operation of stamp duty on the part of the Commissioners, the date which is the date of payment of the stamp duty, interest, surcharge or penalty, as the case may be, which has given rise to that repayment;

‘repayment’ has the same meaning as in section 159A;

‘valid claim’ shall be construed in accordance with section 159A(3).