Section 13-407 - Sales and use tax assessment when records not kept or resale certificate not obtained(a) If a person or governmental unit fails to keep the records required under § 11-504 of this article, the Comptroller may:(1) compute the sales and use tax by using a factor that the Comptroller develops by: (i) a survey of the business of the person or governmental unit, including any available records;(ii) a survey of other persons or governmental units engaged in the same or similar business; or(b)(1) If a person or governmental unit fails to obtain a proper resale certificate on or before the date stated in a notice of intent to assess the sales and use tax under § 11-408(b) of this article, the Comptroller may assess the sales and use tax on the sale.(2) An assessment under this subsection is final.