What the Law Says ?
Registering the documents relating to the transfer, sale, lease or any other form of disposal of a property is compulsory by law under section 17 of the Indian Registration Act, 1908. The registration of an agreement to buy or sell a flat in Maharashtra is compulsory under Section 4 of the Maharashtra Ownership Flats Act, 1963.
Once a property is registered, it means that the person in whose favour the property is registered is the lawful owner of the premises and is fully responsible for it in all respects.
If the required documents are not duly registered, then Section 49 of the Indian Registration Act, 1908 states that the documents will not have any bearing on the property, and that they do not confer any transaction rights over the property. In other words, the law does not recognize unregistered owner and does not give him any rights over the property.