Md. Code Ann., Tax-Prop. § 1-201 — § 1-201

(a) A requirement in this article that a document be under oath means that the document shall be supported by a statement made under the penalties of perjury that the contents of the document are true to the best of the knowledge, information, and belief of the individual making the statement.
(b) The oath or affirmation shall be made:
(1) before an individual authorized to administer oaths, who shall certify in writing to have administered the oath or taken the affirmation; or
(2) by a signed statement that:
(i) is in the document or attached to and made part of the document; and
(ii) is expressly made under the penalties for perjury.
(c) If the procedures provided in subsection (b)(2) of this section are used, the affidavit subjects the individual making it to the penalties for perjury to the same extent as an oath or affirmation made before an individual authorized to administer oaths.