If the Assessing Authority, upon information which has come into his possession, is satisfied that any dealer who has been liable to pay tax under the Act in respect of any period, has failed to get himself registered, the Assessing Authority shall proceed in such manner as may be prescribed to assess to the best of his judgement the amount of tax due from the dealer in respect of such period and all subsequent periods and in making such assessments shall give the dealer reasonable opportunity of being heard.