Gov (search: IT-2104-I) or scan the QR code below. The Tax Board's primary responsibility is the certification of property tax assessments.Other functions of the Tax Board are the equalization of assessments. Taxes are due on February 1st, May 1st, August 1st, and November 1st with a grace period extending to the 10th of each quarter. Complete Form W-4 so that your employer can withhold the correct federal income tax from your pay. Give Form W-4 to your employer. The Commissioner is also responsible for accurately assessing all personal property and for overseeing the State income tax filing process in Middlesex County.