Wis. Stat. § 72.33: Adjustments.

(2) A person who is entitled to a refund of the federal estate tax or liable for additional payments of that tax shall, within 30 days after receiving notice of that fact, do the following:

(a) Submit to the department copies of any additional papers or supporting documents required to be filed with the federal government.

(b) Compute the amount of any refund or additional tax and report the same to the department, together with any additional tax due.

(3) Any refund which the department finds due shall be made within 30 days after receipt of the report under sub. (2) (b).