law: 27. Interest.
  (1) If any dealer fails to pay the tax due as required by sub-section (3) of section 21, he shall, in addition to the tax (including any penalty) due, be liable to pay simple interest on the amount so due at one per cent. per month from the date immediately following the last date for submission of the return under sub-section (2) of the said section for a period of one month, and at one and a half per cent. per month thereafter for so long as he continues to make default in such payment or till the date of completion of assessment under section 23, whichever is earlier.
  (2) When a dealer or a person is in default or is deemed to be in default in making the payment of tax, he shall, in addition to the amounts payable under section 23 or section 24, be liable to pay simple interest on such amount at one per cent. per month from the date of such default for a period of one month, and at one and a half per cent. per month thereafter for so long as he continues to make default in the payment of the said amount.
  (3) Where as a result of any final order the amount of tax (including any penalty) due or in default is wholly reduced, the amount of interest, if any, paid shall be refunded, or if such amount is varied, the interest due shall be calculated accordingly:
  Provided that where any amount of tax payable is enhanced by any such order, interest shall be payable on the amount by which the tax is enhanced after the expiry of a period of three months from the date of the order:
  Provided further that where the realisation of any amount remains stayed by the order of any court or authority and such order is subsequently vacated, interest shall be payable also for any period during which such order remained in operation.
  (4) The interest payable under this section shall be deemed to be tax due under this Act.