(3)(a)If the Commissioner is not satisfied that the returns furnished in respect of any period are correct and complete and he thinks it necessary to require the presence of the dealer or the production of further evidence, he shall serve on such dealer in the prescribed manner a notice requiring him on a date and at a place specified therein either to attend and produce or cause to be produced all evidence on which such dealer relies in support of his returns, or to produce such evidence as is specified in the notice.(b)On the date specified in the notice, or as soon as may be thereafter, the Commissioner shall, after considering all the evidence which may be produced, assess the amount of tax due from the dealer.