Md. Code, Tax-Prop. § 9-219

(a) The Mayor and City Council of Baltimore City or the governing body of a county or of a municipal corporation may grant, by law, a property tax credit against the county or municipal corporation property tax imposed on rental dwellings of owners who provide reduced rents for any tenant who: (1) is at least 65 years old; (2) has been found permanently and totally disabled and has qualified for benefits under: (i) the Social Security Act; (ii) the Railroad Retirement Act; (iii) any federal act for service members; or (iv) any federal retirement system; or (3) has been found permanently and totally disabled by a county health officer or the Baltimore City Commissioner of Health. (b) The county or municipal corporation may provide, by law, for: (1) the specific requirements for eligibility for a tax credit authorized under this section; (2) additional limitations on eligibility for the credit; (3) the amount and duration of the credit; and (4) any other provision appropriate to implement the credit.