Maryland Code, Tax-General § 10-808

(b)(1) If an individual required to file an income tax return is a minor, the individual's parent or guardian shall file the return.

(2) If an individual required to file an income tax return is a disabled person as defined in § 13-101 of the Estates and Trusts Article, the individual's guardian shall file the return.

(1) by the personal representative of the individual's estate;

(2) if there is no personal representative, by the individual's surviving spouse;

(3) jointly by the individual's surviving spouse and the personal representative of the individual's estate; or

(4) jointly by the personal representative of the individual's estate and the personal representative of the deceased spouse's estate.