Wis. Stat. § 182.45

On or before the first day of February of each year, the corporation shall make an annual report of its activities for the preceding calendar year to the department of financial institutions. Each such report shall set forth a complete operating and financial statement covering its operations during the year. The corporation shall cause an audit of its books to be made at least once each year by certified public accountants and the cost thereof may be treated as a part of the cost of the construction or of operations of the project.