After the vesting date and before the final publication of the compensation assessment roll, ad interim payment to the outgoing intermediary may be made as follows:--
         (a) the compensation officer shall calculate the probable amount of compensation payable to him;
         (b) two and a half per cent. of such probable amount shall be paid ad interim to each intermediary in cash every year until such time as the compensation assessment roll is finally published;
         (c) if there is any dispute as to the title of any person to receive the amount or as to the apportionment of it, the amount shall be kept in deposit in the manner prescribed until the dispute is finally determined; and on such determination, the compensation officer shall pay the amount or the portion thereof to the person or persons entitled to receive the same.