Md. Code, Tax - General § 11–504

(a) A vendor shall keep:

(1) complete and accurate records of:

(i) all retail sales and sales for use; and

(ii) the sales and use tax collected; and

(2) other records in the form that the Comptroller requires by regulation, including bills of lading and invoices.

(b) A vendor shall make the records under subsection (a) of this section available for inspection and examination by the Comptroller at any time during business hours.

(c) A vendor shall keep the records required under subsection (a) of this section for 4 years, unless the Comptroller:

(1) consents in writing to an earlier destruction of the records; or

(2) requires in writing that the records be kept longer.