Is registering a rent agreement mandatory?
For a term of 12 months or more, registration is generally required. Shorter agreements usually are not — which is why 11-month agreements are everywhere.
Under the Registration Act 1908, a lease of immovable property from year to year, or for a term exceeding one year, must be registered. In practice that means an agreement of 12 months or longer is registered at the Sub-Registrar's office, with stamp duty and a registration fee paid according to the state's rates.
An agreement shorter than that is usually executed on stamp paper without registration. Some states have their own requirements layered on top — Maharashtra, for instance, requires registration of leave and licence agreements regardless of the shorter term — so the state matters.
An unregistered agreement that should have been registered is weak where it counts: it can be difficult to rely on as evidence of its own terms in a dispute. If the tenancy is genuinely long-term, registering it protects both sides.
General information about renting in India, not legal advice. Rules differ by state — check with your local Sub-Registrar office or a lawyer before acting on this.