Wis. Stat. § 76.64 — Quarterly installments

Insurers shall pay installments of the total estimated payment under ss. 76.60 , 76.63 , 76.65 and 76.66 on or before April 15, June 15, September 15 and December 15. Every insurer shall make a return for the preceding calendar year on or before March 1 setting forth the information that the commissioner of insurance reasonably requires, on forms prescribed by the commissioner. On or before March 1, the insurer shall pay any additional amount due for the preceding calendar year. Overpayment will be credited on the amount due April 15.