Section 18 of the Act lays down the instruments of which registration is optional. Some of these instruments are listed as under :-
a) Instruments ( other than instruments of gifts and wills) relating to the transfer of an immovable property, the value of which is less than one hundred rupees.
b) Instruments acknowledging the receipt or payment of any consideration.
c) Lease of an immovable property for a term not exceeding one year.
d) Instruments transferring any decree or order of a court where the subject matter of such decree or order is an immovable property, the value of which is less that one hundred rupees.