(1) An estimation or assessment of tax under section 110 or 111 may be made at any time not later than 4 years -

(a) after the end of the taxable period to which the estimate or assessment relates, or

(b) if the period for which the estimate or assessment is made consists of 2 or more taxable periods, after the end of the earlier or earliest taxable period within that period.

(2)

(a) Subject to paragraphs (b) and (c), in this subsection "neglect" means negligence or a failure to give any notice, to furnish particulars, to make any return or to produce or furnish any invoice, credit note, debit note, receipt, account, voucher, bank statement, estimate or assessment, statement, information, book, document, record or declaration required to be given, furnished, made or produced by or under this Act or regulations.

(b) A person shall be deemed not to have failed to do anything required to be done within a limited time if the person did it within such further time (if any) as the Revenue Commissioners may have allowed.

(c) Where a person had a reasonable excuse for not doing anything required to be done, he or she shall be deemed not to have failed to do it if he or she did it without unreasonable delay after the excuse had ceased.