Maryland Code, Election Law § 2-302

(i) on each day that is a county government workday in its county;

(ii) on each election day; and

(iii) until 9 p.m. on the last day for the filing of a certificate of candidacy for an election conducted in the county, if a certificate can be filed with the local board.

(i) may be the same as the regular business hours of its county government; or

(ii) for the convenience of the public, may be different from the regular business hours of its county government, except that the number of business hours the office is open each business day must be at least equivalent to the number of business hours that the county government is open.