Maryland Code, Election Law § 5-703

(c)(1) A candidate for public office who seeks nomination by petition shall file a declaration of intent to seek nomination by petition.

(2) The declaration of intent shall be filed with the board at which the candidate files a certificate of candidacy under Subtitle 3 of this title.

(3) The declaration of intent shall be filed as follows:

(4) A candidate who seeks nomination by petition may not be charged a fee for filing the declaration of intent.

(d)(1) A candidate for public office who seeks nomination by petition shall file a certificate of candidacy not later than 5 p.m. on the first Monday in August in the year of the general election for the office.

(2) Except for the time of filing, the certificate of candidacy for a candidate who seeks nomination by petition shall comply with the requirements for a certificate of candidacy under Subtitle 3 of this title.

(e)(1) A candidate who seeks nomination by petition may not have the candidate's name placed on the general election ballot unless the candidate files with the appropriate board petitions signed by the lesser of 10,000 registered voters or 1% of the total number of registered voters who are eligible to vote for the office for which the nomination by petition is sought, except that the petitions shall be signed by at least 250 registered voters who are eligible to vote for the office.

(2) The petitions shall be filed as required in Title 6 of this article.

(3) The number of registered voters required to satisfy the requirements of paragraph (1) of this subsection shall be determined as of January 1 of the year of the primary election for which the nomination is sought.

(f)(1) Except as provided in paragraph (2) of this subsection, a petition that contains the required number of signatures specified under subsection (e)(1) of this section shall be filed with the appropriate board by 5 p.m. on the first Monday in August in the year in which the general election is held.

(2) In a special election to fill a vacancy in the office of Representative in Congress, a petition that contains the required number of signatures shall be filed with the State Board by 5 p.m. on the day of the special primary election.