s259 of the LPA states
An amount of trust money held by a law practice is an unclaimed amount if:
(a) the amount has been held by the practice for a period of at least 2 years and during that period the practice has had no knowledge of the existence or the address of the person on whose behalf the amount is held; or
(b) the person has refused to accept payment of the amount when tendered.
In approving this application, the Society requires verification that the practice has undertaken due diligence in regard to locating clients and cancelling any stale cheques.