For month-to-month rentals, the landlord can raise the rent (subject to any rent control laws) with proper written notice, typically 30 days.
With a fixed-term lease, the landlord may not raise the rent during the lease, unless the increase is specifically called for in the lease, or unless the renter agrees. At the end of the lease, the landlord may raise the rent, subject to any rent control laws.
Few communities have rent control laws. In fact, communities in only five states -- California, the District of Columbia, Maryland, New Jersey, and New York -- have rent control laws that limit the amount of rent landlords may charge.
Rent control ordinances (also called rent stabilization or maximum rent regulation) limit the circumstances and the times that rent may be increased, and the percentage by which rent can be increased each year. Landlords and tenants in New York City, Newark, San Francisco, and other cities with rent control should be sure to get a current copy of the rent control ordinance and any regulations interpreting it. Check the phone book for the address and phone number of the local rent control board or contact the mayor or city manager's office.
For more articles about your legal rights when renting or leasing an apartment, see Nolo's Renting a House or Apartment section.