Maryland Code, Insurance § 15-204

(a) If a policy of health insurance establishes, as an age limit or otherwise, a date after which the coverage provided by the policy will not be effective, and the date falls within a period for which the insurer accepts a premium for the policy, or if the insurer accepts a premium for the policy after that date, the coverage provided by the policy continues in effect until the end of the period for which the insurer has accepted the premium.

(b) If the age of the insured is misstated and, according to the correct age of the insured, the coverage provided by the policy would not have become effective or would have ceased before the acceptance of a premium for the policy, the liability of the insurer is limited to the refund, on request, of the premiums paid for the period not covered by the policy.