Vested interest is not:

Transfer of Property Act  S. 19. Vested interest .—Where, on a transfer of property, an interest therein is created in favour of a person without specifying the time when it is to take effect , or in terms specifying that it is to take effect forthwith or on the happening of an event which must happen, such interest is vested, unless a contrary intention appears from the terms of the transfer. A vested interest is not defeated by the death of the transferee before he obtains possession. Explanation.—An intention that an interest shall not be vested is not to be inferred merely from a provision whereby the enjoyment thereof is postponed, or whereby a prior interest in the same property is given or reserved to some other person, or whereby income arising from the property is directed.