(1) (a) Where any registered dealer or any other dealer has furnished returns but has not paid the tax as per return or within the time allowed by or under the provisions of this Act, he shall be liable to pay interest on the whole or that part of the amount of tax which was not paid as per returns within the time as aforesaid, at the rate of one and a quarter per cent per month from the date by which he was required to pay the tax by or under the provisions of this Act for a period of three months and at one and a half per cent per month thereafter until the date of payment: (b) Where any registered dealer or any other dealer has furnished a revised return as provided under sub section (3) of section 7, which revised return shows that amount of tax larger than that already paid is payable, such dealer shall be liable to pay interest on the excess amount of tax at such rate and for such period as provided in clause (a) of this sub section as if such amount of tax payable as per the revised return was the amount of tax payable according to the original return; . . . lt was contended that as clauses (a) and (b) of sub section (1) of section 11B extracted above were declaratory in character and merely explained what the Legislature meant by enacting section 11B as it stood before the substitution, the assessee was liable to pay interest on the amount of tax payable in respect of freight charges under clause (b) of sub section (1) of the new section 11B. Since we are of the view that the assessee was liable to pay interest on the tax in question under section 11B of the Act as it stood prior to tile amendment, we do not find it necessary to express any opinion on this alternative contention urged on behalf of the State Government.