Wis. Stat. § 78.67 — Timely filing

When the final date provided in this chapter for the filing of any report or claim or for the remittance of any tax or penalty falls on a Saturday, Sunday or legal holiday, the next secular or business day shall be the final date. The provisions on timely filing under s. 71.80 (18) apply to the reports, claims and remittances under this chapter.