Maryland Code, Insurance § 15-411

(a) Each group health insurance contract or policy that is issued by an insurer or nonprofit health service plan shall provide continuous open enrollment for the purpose of allowing a married employee who is enrolled under the contract or policy to alter the terms of the employee's coverage to include the employee's spouse or children if the employee's spouse loses coverage under another group health insurance contract or policy because of the involuntary termination of the spouse's employment other than for cause.

(b) A group health insurance contract or policy may not require evidence of insurability for a spouse who qualifies for group health insurance coverage under this section.

(c) A married employee who wishes to alter the terms of the employee's coverage under this section shall notify the employer within 6 months after the date on which the coverage of the employee's spouse under another group health insurance contract or policy terminates.