Md. Code, Tax - General § 11–235

(a) The sales and use tax does not apply to the cleaning of a commercial or industrial building if the building is owned by a common ownership community or retirement community and used for:

(1) classrooms;

(2) dining;

(3) exercise;

(4) food preparation or cooking;

(5) meetings or gatherings;

(6) offices used by the common ownership community for management of the community;

(7) recreation;

(8) security;

(9) sports;

(10) storage; or

(11) any other common use.

(b) The exemption under subsection (a) of this section does not apply to the cleaning of a commercial or industrial building or the proportionate share of the building that is used for a purpose that requires the collection of the sales and use tax under this title.