Wis. Stat. § 24.73: Extension of loan.

All loans made or which may be made from any state trust funds to any borrower may be extended for such time and upon such terms as may be agreed upon by and between the board and such borrower; provided, however, that no loan shall be extended upon which there is any default in the payment of interest at the time of making application therefor, nor to any period beyond 20 years from its inception, nor at any rate of interest less than the minimum established by law.