Maryland Code, Tax-General § 13-407

(1) compute the sales and use tax by using a factor that the Comptroller develops by:

(2) assess the tax due.

(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.