643.2. No tax is payable in respect of the consideration for a supply of a service of a personal representative in respect of the administration of a succession, or a service of a trustee, receiver or liquidator, to the extent that the consideration relates to any part of the service that was performed before 1 July 1992 and does not become due(1) in the case of the service of a personal representative, until it is approved by all beneficiaries of the succession or in accordance with the terms of the trust binding the personal representative;
(2) in the case of the service of a trustee, until a date determined under the terms of the trust or an agreement in writing for the supply; or
(3) in any case, until it is allowed, directed or ordered by a court.