Corporations.
(a)#
Except as provided in s. 71.29 (7), in the case of any underpayment of estimated tax by a corporation under s. 71.29 or 71.48, there shall be added to the aggregate tax for the taxable year interest at the rate of 12 percent per year on the amount of the underpayment for the period of the underpayment. In this paragraph, “period of the underpayment” means the time period from the due date of the installment until either the date on which the corporation is required to file for federal income tax purposes, not including any extension, under the Internal Revenue Code or the date of payment, whichever is earlier. If 90 percent of the tax shown on the return is not paid by the date on which the corporation is required to file for federal income tax purposes, not including any extension, under the Internal Revenue Code, the difference between that amount and the estimated taxes paid, along with any interest due, shall accrue delinquent interest under s. 71.91 (1) (a).