(1) Late payment. An insurer that fails to make quarterly payments under s. 76.64 of at least 25% of either the total tax paid for the previous calendar year or 80% of the actual tax for the current calendar year is liable, in addition to the amount due, for interest of 1.5% of the amount due and unpaid for each month or part of a month that the amount due, together with any interest, remains unpaid.
(2) Negligence. An insurer that fails to pay an amount due, or file a return required, under s. 76.64 , unless the insurer shows that the failure is due to reasonable cause and not due to willful neglect, is liable for the greater of the following amounts:
(a) Five hundred dollars.
(b) Five percent of the amount due for each month or fraction of a month during which the failure continues, but not more than 25% of the amount due.