Notwithstanding anything contained in this Act, where the Commissioner has a reason to believe that any person who is unregistered casual trader and/or nonresident dealer and is likely to evade the payment of tax due, the Commissioner may, if deemed necessary, proceed to assess such persons and if it is not practicable to issue a notice for assessment, may proceed to assess such person on the spot and direct such person to deposit the amount of tax in such manner and by such date as may be indicated in the Order.