Section 76.645 - Penalties(1) LATE PAYMENT. An insurer that fails to make quarterly payments under s. 76.64 of at least 25 percent of either the total tax paid for the previous calendar year or 80 percent of the actual tax for the current calendar year is liable, in addition to the amount due, for interest of 1.5 percent 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, and upon a showing by the department of revenue under s. 73.16(4), 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 percent of the amount due.