Rent & fees
Can my landlord raise rent as much as they want?
In most states, yes - with proper notice there's no cap. But a few states (and many cities) cap increases, and an increase can never be retaliatory or discriminatory.
Most of the U.S. has no statewide limit on how much rent can rise between lease terms. The protections that do exist are notice periods, statewide caps in a handful of states (Oregon, California, Washington), local rent control in many cities, and the universal rules against raising rent to retaliate or discriminate.
Even in no-cap states, a shocking increase right after you requested repairs or reported a violation can be challenged as retaliation - the timing itself is evidence.
The details vary by state. See statewide caps and notice rules for your state →
Do something about it
The Rent increase checker turns this answer into action.
General educational information, not legal advice. Laws vary by state and city and change over time - for a specific situation, contact a local tenant-rights organization.