Section 56(1)(a) in The Gujarat Housing Board Act, 1961
(a)that the person authorised to occupy any Board premises has-(i)not paid rent lawfully due from him in respect of such premises for a period of more than [six months] [These words were substituted for the words 'two months' by Gujarat 1 of 1973, section 40.], or(ii)sub-let, without the permission of the Board, the whole or any part of such premises, or