Q: I rented a room at a certain price per month, without a specified time limit. Can the landlord raise the rent after three months?
A: When the rental agreement specifies a time frame, neither side can retract or unilaterally change the rent during the specified time, even if there is a significant, unexpected change in rental rates (C.M. 312:1, 10; 316:1).
If the rental agreement simply states the fee per day, month, week or year, without specifying a time, the price continues so long as the renter remains. However, either side can retract or demand to adjust the rental fee in order to continue the rental. (Real-estate rental often has a 30-day or one-year minimum, in accordance with local practice — C.M. 312:9; 341:1; Aruch Hashulchan 312:12.)
If there was a specified time frame and the renter continued residence without explicitly renewing the contract, there is a dispute whether the owner can retroactively charge the current, higher rate without having notified the renter beforehand (see Shach 312:10; Machaneh Ephraim, Sechirus #11).