(a) the tenancy is bona fide;
(b) the defaulting tenant has vacated, or steps have been taken to compel him to vacate the property;
(c) the defaulting tenant is not in occupation of any other property of the assessee;
(d) the assessee has taken all reasonable steps to institute legal proceedings for the recovery of the unpaid rent or satisfies the Assessing Officer that legal proceedings would be useless.
Reference/Source: Check at Income Tax site for latest version of the Rules - link