In areas without rent control, there is no limit on the amount you can increase the rent of a month-to-month or other periodic tenant.  Similarly, there is no restriction on the period of time between rent increases.  You can legally raise the rent as much and as often as good business dictates.  Of course, common sense should tell you  that if your tenants think your increases are unfair, you may end up with vacant units or a hostile group of tenants looking for ways to make you miserable.  As a courtesy, you may wish to tell your tenants personally, perhaps explaining the reasons, although reasons are not legally necessary, except in areas covered by rent control.

You cannot legally raise a tenant’s rent as retaliation-for example, in response to a legitimate complaint or rent-withholding action or in a discriminatory manner. The laws in many states actually presume retaliation if you increase rent soon-typically, within three to six months-after a tenant’s complaint of defective conditions.

One way to protect yourself from charges that ordinary rent increases are retaliatory or discriminatory is to adopt a sensible rent-increase policy and stick to it.  Make sure to inform your tenants about the rent increase in advance and apply the increase uniformly to all your tenants.

Except in cities with rent control, your freedom to raise rent depends primarily on whether the tenant has a lease or a month to month rental agreement.  When the lease or rental agreement expires, you can present the tenant with a new lease that has a higher rent or other changed terms.  It is always safer to give the tenant at least a month or two advance notice.