Md. Code, Tax - Property § 2–218

(a) The Department may request documentation to verify that a dwelling is the principal residence of a homeowner.

(b) The documentation requested under subsection (a) of this section may include, but is not limited to, requiring an individual to execute a sworn affidavit regarding residency for the purposes of:

(1) voting;

(2) driver’s license address; and

(3) income tax filing.

(c) Failure to provide the requested information under this section within 30 days from the date of a request shall result in a dwelling being designated as not a principal residence for purposes of this article.