Maryland Code, Tax-Property § 14-904

(a) A person who submits a written refund claim to the appropriate collector for State property tax erroneously or mistakenly paid to the collector is eligible for a refund from the State Treasury of the amount of State property tax paid that exceeds the amount that is properly and legally chargeable to or collectible from the person.

(b) If the assessment on which State property tax is payable has become final and has not been appealed as provided by Subtitle 5 of this title, a person is eligible for a refund of State property tax only if the person paid a tax bill that is erroneous because of a mathematical error, mechanical error, error in the property description, or other clerical error made by the taxing authority or assessing authority, and not because of an error of valuation.