Missing Tenant.

Tenancy Types and Management

Hi, I have a tenant to whom I have served a Section 21 which now as 5 weeks to run. Rent is in excess of two months in arrears and I have been unable to contact him for over a week leaving notices through the door and sending a recorded delivery letter. The rent is due again in a week. On the assumption that he does not pay or contact me I intend to enter the property. Should the property show evidence that he as not been there for a while I intend to change the locks, clean up the property and rent it out again. Is this legal? If not what is the likely outcome of prosecution and the likely penalty. Not the maximum but the likely.