Maryland Tax - General Section 10-812

      (a)      A corporation exempt from income tax under § 10-104 of this title shall file an income tax return if the corporation:

            (1)      has unrelated business taxable income, as defined under § 512 of the Internal Revenue Code;

            (2)      is exempt from taxation under § 501(c)(2) of the Internal Revenue Code; or

            (3)      is an S corporation that is incorporated or does business in the State.

      (b)      An organization that is exempt from taxation under § 501(c)(3) or (4) of the Internal Revenue Code may file an income tax return to claim a refund under § 10-714 of this title.