Any person who fails to file a return by the date under s. 72.30 (1) is subject to a penalty of 5 percent of the tax due under s. 72.02 but not less than $25 nor more than $500.
Wis. Stat. § 72.235
Failure to file
1991 a. 39.
Official source: Wisconsin State Legislature. Reproduced from public-domain Wisconsin statutes; confirm against the official source for the current text. Not legal advice.