Where an accommodation is allotted to a person under [sub-section (2) of Section 39 of Section 40-A] he shall be deemed to be a tenant of the landlord of such accommodation and shall be liable to pay therefor from the date of the vacation of the accommodation-
(a) where the accommodation before it became vacant was in occupation of a tenant, the rent payable by such tenant;
(b) where the accommodation was not previously in occupation of a tenant, such rent as may be determined by Rent Controlling Authority in accordance with the principles specified in Section 7:
Provided that where, in consequence of any proceedings under the first proviso to subsection (2) of Section 39, the accommodation remains unoccupied by the allottee for a period exceeding fifteen days from the date of vacation thereof, the allottee shall be liable to pay rent only for a period of fifteen days out of the period during which it remained so unoccupied.