If an interest assessment is required under this section, interest is computed at the rate specified in section 270C.40.
If a tax is not paid within the time specified by law for payment, the unpaid tax bears interest from the date the tax should have been paid until the date the tax is paid.
If an extension of time for payment has been granted, interest must be paid from the date the payment should have been made if no extension had been granted, until the date the tax is paid.
If a taxpayer is liable for additional taxes because of a redetermination by the commissioner of revenue, or for any other reason, the additional taxes bear interest from the time the tax should have been paid, without regard to any extension allowed, until the date the tax is paid.
(a) Interest must be paid at the rate specified in section 270C.40 on an overpayment that is refunded or credited to a taxpayer more than 30 days after a refund request is made. Interest does not apply to the 30-day period.
(b) In the case of an erroneous refund, interest accrues from the date the refund was paid unless the erroneous refund results from a mistake of the Department of Revenue or the county, then no interest or penalty is imposed unless the deficiency assessment is not satisfied within 60 days of the order.
Notwithstanding section 549.09, if judgment is entered in favor of the commissioner of revenue or a county with regard to any tax under this chapter, the judgment bears interest at the rate specified in section 270C.40 from the date the judgment is entered until the date of payment.