(1) If the prescribed authority is satisfied, either on the basis of audit conducted under sub-section (3) of section 26 or otherwise, that reasonable grounds exist to believe that, in respect of any assessment under this Act or under the Bihar Finance Act, 1981 (Bihar Act 5 of 1981), as it stood before its repeal by section 94, during any period, any sale or purchases of goods liable to tax under this Act or the said Act, for any reason, has been underassessed or has escaped assessment, or has been assessed to tax at a lower rate, or any deduction therefrom has been wrongly made, or an input tax credit has incorrectly been claimed, the prescribed authority shall, in such manner as may be prescribed and after serving on the dealer a notice in the form and in the manner prescribed, proceed to assess or re-assess, as the case may be, the tax payable by such dealer within four years from the expiry of the year during which the original order of assessment or re-assessment was passed, in a case where the dealer has concealed, omitted or failed to disclose full and correct particulars of such sale or purchase or input tax credit, and the provisions of this Act shall, so far as may be, apply accordingly as if the notice under this sub-section was a notice under section 27:
     Provided that the amount of tax shall be assessed or re-assessed after allowing such deductions as were allowable during the said period and at the rates at which it would have been assessed had the turnover not escaped assessment.
     (2)(a) The prescribed authority shall, in a case where the dealer has concealed, omitted or failed to disclose full and correct particulars of such sale or purchase or input tax credit, direct that the dealer shall, besides the amount of interest payable under sub-section (10) of section 24, pay by way of penalty, a sum equal to three times the amount of tax which is or may be assessed on the turnover of sale or purchase which escaped assessment.
         (b) The penalty imposed under clause (a) shall be in addition to the amount of tax, which is or may be assessed on the turnover of sale or purchase which escaped assessment.
     (3) Any assessment or re-assessment made and any penalty imposed under this section shall be without prejudice to any action, which is or may be taken under section 81.