Wis. Admin. Code Department of Transportation § Trans 100.19
The Department conducts system wide "purges" of its driver database once or twice per year, usually over weekends around the 1st of the year and the 1st of July. A record entry is removed if it meets purge criteria on the date a purge is conducted. Entries are not removed on anniversary dates, but rather, in the first purge conducted after the appropriate anniversary date.