Annual tax bills and the first installment of semi-annual bills are due on or before September 30th and become delinquent on October 1st. The second installment is due December 31st and becomes delinquent January 1st. Delinquent bills are subject to interest and penalty at the rate of 1 2/3% (1.667 per month on the unpaid balance) per month until paid in full. The total late charge is 20% annually as set by Resolution following County Council action, and which is composed of 8% interest and 12% penalty. Interest and penalty are calculated on the net amount of the bill, after any credits are applied. Delinquent taxes will result in the sale of the property tax lien through a public tax lien sale on the second Monday in June of the subsequent calendar year. Taxpayers receive a delinquency or tax lien sale notice in April. Accounts eligible for the tax lien sale are listed for four consecutive weeks preceding the tax lien sale in a Montgomery County newspaper and are subject to a $50 advertising fee. Property tax accounts taken to tax lien sale may be subject to additional legal costs that are incurred by the new tax lien certificate holder. To reach an office representative, contact 311 during regular business hours.

Payment due dates are pursuant to Maryland State Law, which also determines how interest and penalty are calculated and applied to an account. Interest and penalties are levied on accounts that are delinquent. Interest and penalties are non-negotiable and cannot be waived.