Where a taxable person is a firm or an association of persons or a Hindu Undivided Family and such firm, association or family has discontinued business––
(a) the tax, interest or penalty payable under this Act by such firm, association or family up to the date of such discontinuance may be determined as if no such discontinuance had taken place; and
(b) every person who, at the time of such discontinuance, was a partner of such firm, or a member of such association or family, shall, notwithstanding such discontinuance, jointly and severally, be liable for the payment of tax and interest determined and penalty imposed and payable by such firm, association or family, whether such tax and interest has been determined or penalty imposed prior to or after such discontinuance and subject as aforesaid, the provisions of this Act shall, so far as may be, apply as if every such person or partner or member were himself a taxable person.