139.— (1) F143[Any deferred amount] shall be payable by the liable person on the occurrence of a relevant event.

(2) The receipt of a windfall gain by a liable person shall be treated as a relevant event and subsection (1) shall apply accordingly.

(3) A liable person shall notify the Revenue Commissioners when he or she receives a windfall gain.

(4) Where the relevant event is the transfer of the relevant residential property by way of a gift or an inheritance, the Revenue Commissioners may allow a deferral to continue where—

(a) the liable person making the gift, or the liable person’s personal representative, as the case may be, notifies the Revenue Commissioners of the making of the gift or inheritance, and

(b) the person who receives the gift or inheritance is eligible for, and makes a valid claim for, a deferral.