Maryland Code, Family Law § 10-121

(b)(1) Any order under this Part III of this subtitle that is passed before July 1, 1985 shall become an immediate and continuing withholding order on all earnings of the obligor that are due on or after the date of the withholding order on the filing by the recipient or support enforcement agency of:

(2) Notice of the filing of the motion and a statement that the support order constitutes an earnings withholding order subject to the conditions of this Part III of this subtitle shall be sent to the obligor by certified mail, return receipt requested and first-class mail, at the last known home address or, if the home address is unknown, the place of employment of the obligor.

(1) if the obligor accumulates support payments arrears amounting to more than 30 days of support, the obligor shall be subject to earnings withholding;

(2) so long as the support order is in effect, the obligor is required to notify the court of:

(3) failure to comply with item (2) of this subsection will subject the obligor to a penalty not to exceed $250 and may result in the obligor's not receiving notice of proceedings for earnings withholding.