Without one of these documents, the asset holders cannot be satisfied as to who has the correct authority to receive the deceased’s assets and may refuse to pay out.
Which one of these is required will depend on whether the deceased left a valid Will.
Grant of Probate
This is effectively a document issued by the Supreme Court of Victoria which formally authorises an executor to manage the estate of a deceased person in accordance with their Will.
Letters of Administration
If there is no Will, then you instead obtain Letters of Administration. This is effectively the same as a Grant of Probate, in terms of authorising someone to administer the estate, and would usually be obtained by the person who is the closest next-of-kin to the deceased.
For more information on the timeframe and requirements for obtaining a Grant of Probate or Letters of Administration, see our article: How Long Does Probate Take?