An AST can be ended at any point after the initial six month period, assuming that any fixed term you originally agreed to is over. You are required to give your tenant a minimum of two months’ notice in writing, to let them know you want your property back and to give them time to make arrangements to vacate. If you have grounds to do so, you might also end the tenancy at any time. These grounds might include anti-social behaviour by the tenant or damage caused to your property, as well as the rent arrears as mentioned above.