The Director of Finance may make an assessment for taxes not remitted by a retailer for any reason specified in Sec. 21.16 of this chapter for making an assessment for unpaid Business Tax. The manner of making and providing notice of such assessment; the right to a hearing and the conduct of such hearing; the preparation and service of findings; filing exceptions; and passing upon exceptions shall be the same as provided in Sec. 21.16 of this chapter.