Yes, but only the principal, not the interest. For example, you have a $10,000 USSB that is now worth $7000 when you roll it over to a Wisconsin 529 plan. You may deduct only the $5000* you bought the bond for.
Reference: https://dfi.wi.gov/Pages/EducationalServices/CollegeSavingsCareerPlanning/CollegeSavingsProgram.aspx
*You would deduct the maximum $3860 and roll over the other $1140 to next year.
