Maryland Tax - General Section 11-701
§ 11-701.
  (a)   In this subtitle the following words have the meanings indicated.
  (b)   (1)   "Engage in the business of an out-of-state vendor" means to sell or deliver tangible personal property or a taxable service for use in the State.
    (2)   "Engage in the business of an out-of-state vendor" includes:
      (i)   permanently or temporarily maintaining, occupying, or using any office, sales or sample room, or distribution, storage, warehouse, or other place for the sale of tangible personal property or a taxable service directly or indirectly through an agent or subsidiary;
      (ii)   having an agent, canvasser, representative, salesman, or solicitor operating in the State for the purpose of delivering, selling, or taking orders for tangible personal property or a taxable service; or
      (iii)   entering the State on a regular basis to provide service or repair for tangible personal property.
  (c)   (1)   "Engage in the business of a retail vendor" means to sell or deliver tangible personal property or a taxable service in the State.
    (2)   "Engage in the business of a retail vendor" includes liquidating a business that sells tangible personal property or a taxable service, when the liquidator holds out to the public that the business is conducted by the liquidator.
  (d)   (1)   "License" means a license issued by the Comptroller:
      (i)   to engage in the business of an out-of-state vendor; or
      (ii)   to engage in the business of a retail vendor.
    (2)   "License" includes a special license issued under § 11-707 of this subtitle.