Primarily it is necessary to understand that not all wills need to be registered. Registration of a will simply means that the maker of the will and the witnesses have appeared before the registering authorities and that their identity has been verified.
Further it should be noted that there is no provision laid down in law for compulsory taking a probate for any registered will. A probate is nothing but the verification form genuineness of the will. It is not always necessary to get a probate order for a will. If there is no dispute between the legal heirs as to the contents of a will they may choose to forgo a probate.
It is therefore not necessary for a registered will to have a probate, though one may be applied for.
The Indian Succession Act, 1925 has no provision making it compulsory to take a probate order in case of an unregistered will. Registration of instruments is governed by the Registration Act, 1908. Under this Act, a will is not needed to be registered, and an unregistered will is also valid.
However, Maharashtra has on its circular issued that an unregistered will is not actually a proof of ownership. Therefore, in cases of wills being implemented in the city of Thane it is necessary to get a probate to implement and to execute an unregistered will. In Maharashtra after death of testator will needs to be probated by filing the petition in appropriate court for probate. It is a process of judiciary through which the authenticity of a WILL is determined by court. Once probate is complete all the properties will be transferred as desired in the will.
Reference: Registration Act, 1908