It is important to register the rent agreement. The Registration Act of India is associable to the whole of India, which means that every agreement of immovable property is basically required to be registered instantly. Also, only the registered lease agreement can be utilized as a piece of evidence in the court in case of any litigation.
If somehow you do register the rent agreement with the authorities, one may end up paying 10 times the original amount as a penalty. To register your rent agreement, you require to visit the sub-registrar office in your locality or city. O should be noted that both, the tenant and the landlord need to be present physically for the registration process along with the witnesses. Prior to this you would require your rental agreement to be printed on a stamp paper. If it is unregistered and for 11 months, it is valid in the eyes of law.
If the rent/lease agreement that you are preparing is for a period of less than 12 months, then, you do not need to register the rent/lease agreement. Typically, non-registered rent/lease agreement is prepared for a period of 11 months. A non-registered agreement can be prepared on Rs 50 or Rs 100 Stamp paper issued by the state. Once, the document is prepared, it is notarized by the local notary. In case there is an issue between owner and the renter, the non-registered rent/lease agreement can also be presented in court of law as a proof of agreement between an owner and renter.
Reference: Section 17 in the Registration Act 1908