If upon examination of such claim for refund, it shall be determined by the director that there has been an overpayment of tax, the amount of such overpayment and the interest on the overpayment, if any, shall be credited against any liability of the taxpayer under any State tax law and if there be no such liability the taxpayer shall be entitled to a refund of the tax so overpaid and the interest on the overpayment, if any. If the director shall reject the claim for refund in whole or in part, the director shall make an order accordingly and serve a notice upon the taxpayer.
N.J.S. § 54:49-15