Can a Pennsylvania landlord raise rent during a fixed-term lease?

Generally no. A fixed-term lease in Pennsylvania locks the rent amount for the lease term. A landlord cannot raise rent during a fixed-term lease without the tenant's written agreement, regardless of whether the market rent has changed. On a month-to-month tenancy or after the fixed term expires, the landlord may increase rent with the required advance notice. Pennsylvania uses 68 P.S. 250.501 tenure-based notice: 15 days for tenancies under 1 year, 30 days for 1 year or more. No state rent cap. Rent changes on month-to-month tenancies follow the same notice ladder.

Source: 68 P.S. 250.501 (Pennsylvania Landlord and Tenant Act 1951)