Notwithstanding anything contained in section 17, where the return submitted under the said section by any dealer, other than a dealer licenced under the Foreign Liquor Rules to serve liquor falling under the Schedule to this Act, is in the prescribed manner and accompanied by the prescribed documents, the return shall, subject to the provisions of section 18 and 19 be deemed to have been accepted as and when the assessing authority acknowledges the receipt of the return in such manner as may be prescribed.