Md. Code, Insurance § 11–213

(a) All homeowner’s insurance rates shall be made in accordance with the principles set forth in this section.

(b) (1) An insurer under a homeowner’s insurance policy may not classify or maintain an insured for a period longer than 3 years in a classification that entails a higher premium because of a specific claim.

(2) For the purpose of determining whether to classify an insured in a classification that entails a higher premium, an insurer may review only a period not greater than 3 years before:

(i) if the policy has not yet been issued:

1. the date of the application; or

2. the proposed effective date of the policy; or

(ii) on renewal of a policy, the effective date of the renewal.

(3) (i) The removal of, reduction of, or refusal to apply a discount is not a violation of this subsection if the claim resulting in the removal of, reduction of, or refusal to apply the discount was filed not more than 5 years before the removal, reduction, or refusal.

(ii) Subparagraph (i) of this paragraph may not be construed to prevent an insurer from granting a claim–free discount to an insured.