I listed a house for lease where the owner just vacated that house and moved to a new home. The owner thinks he doesn’t have to rekey the locks since he has been the only occupant of that house since it was built. Is the landlord required to rekey the locks when we lease the property?

Yes. The Texas Property Code requires that a landlord rekey the locks no later than the seventh day after each tenant turnover date. “Tenant turnover date” is defined as the date a tenant moves into a dwelling under a lease after all previous occupants have moved out. The term does not include dates of entry or occupation not authorized by the landlord. This means that your client, as the landlord and last occupant of the property, would have to rekey the locks no later than the seventh day after a new tenant moves into the home.