Normal.

In assessing taxes interest shall be added to such taxes at 12 percent per year from the date on which such taxes if originally assessed would have become delinquent if unpaid, to the date on which such taxes when subsequently assessed will become delinquent if unpaid.

Except as otherwise specifically provided, in crediting overpayments of income and surtaxes against underpayments or against taxes to be subsequently collected and in certifying refunds of such taxes interest shall be added at the rate of 3 percent per year from the date on which such taxes when assessed would have become delinquent if unpaid to the date on which such overpayment was certified for refund except that if any overpayment of tax is certified for refund within 90 days after the last date prescribed for filing the return of such tax or 90 days after the date of actual filing of the return of such tax, whichever occurs later, no interest shall be allowed on such overpayment. For purposes of this section the return of such tax shall not be deemed actually filed by an employee unless and until the employee has included the written statement required to be filed under s. 71.65 (1). However when any part of a tax paid on an estimate of income, whether paid in connection with a tentative return or not, is refunded or credited to a taxpayer, such refund or credit shall not draw interest.

Any assessment made as a result of the adjustment or disallowance of a claim for credit under s. 71.07, 71.28 or 71.47 or subch. VIII or IX, except as provided in sub. (2) (c), shall bear interest at 12 percent per year from the due date of the claim.