(1) If in consequence of definite information which has come into his possession, the Assessing Authority discovers that the turnover of the business of a dealer has been under-assessed or escaped assessment in any year, the Assessing Authority may, at any time within three years from the date of assessment under section 21, proceed to re-assess the tax payable on the turnover which has been under-assessed or has escaped assessment:

Provided that the Assessing Authority may also take action to impose the penalty and interest under this Act:

Provided further that no order of re-assessment or imposition of penalty and interest shall be made unless the dealer is afforded a reasonable opportunity of being heard in the prescribed manner.

(2) The Assessing Authority or any such Authority as may be prescribed may, at any time, within one year from the date of any order passed by him and subject to such conditions as may be prescribed, rectify any clerical or arithmetical mistake apparent from the record.