(a)petty amounts up to fifty rupees in any single case of assessment, may be written off without any certificate of irrecoverability as mentioned in the preceding provision Subject to the condition that such amount is certified to be irrecoverable by the Secretary [***] [Omitted 'or any other officer of the Board, to whom the powers under Rule 33B have been delegated' by Notification No. G.S.R. 1513(E), dated 13.12.2017 (w.e.f. 1.8.1955).]