Wis. Stat. § 24.21: Accounts with purchasers.

The board shall open and keep an account with each purchaser for every lot or tract of land that is sold, either at public or private sale, in books kept for that purpose, in which the board shall charge the purchaser with the whole purchase money and give the purchaser credit for all the purchaser’s payments, making proper charges for interest as it becomes due, and for all taxes returned to it as unpaid by the proper officer. Upon all payments being completed and the patent issued the account shall be balanced.