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

Generally no. A fixed-term lease in Texas 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. Texas has no statewide statutory advance notice for rent increases. Lease terms govern. Default practice is 30 days written notice on a month-to-month tenancy, matching the Tex. Prop. Code 91.001 termination rule. No state rent cap, and local rent control is preempted.

Source: Lease-based; Tex. Prop. Code 91.001 (30-day month-to-month termination default)