Maryland Code, Tax-Property § 10-210

(a) If on or before September 1 of a taxable year the Department has not notified a county or municipal corporation of any particular personal property assessment, or any operating property assessment, the Mayor and City Council of Baltimore City or the governing body of the county or of the municipal corporation may authorize, by law, the payment of estimated property tax under subsection (b) of this section.

(c) If the property tax paid under this section is less than the tax finally determined, the collector shall send a bill to the taxpayer for the difference.