Why are rent agreements in India usually 11 months?
Because 12 months or more triggers mandatory registration — 11 months keeps the paperwork and cost down.
The Registration Act 1908 requires registration for leases of a year or more. An 11-month agreement sits just under that line, so landlords and tenants avoid the registration process, the fee and the stamp duty that a longer term would attract. That is the whole reason the number is so common.
It also suits both sides commercially. The landlord can revisit the rent within a year, and the tenant isn't locked into a long commitment. Most 11-month agreements are simply renewed, often with an escalation clause that sets the increase in advance.
The trade-off is security. An 11-month agreement gives a tenant less certainty than a registered long lease, and gives the landlord less certainty of occupancy. For a tenancy both sides expect to last years, a registered agreement is worth the cost.
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.