17 N.C. Admin Code 06D .0201 - General

Interest may be due for underpayment of estimated income tax. The interest is computed separately for each payment period, therefore an individual may owe interest for an early period even if that individual later paid enough to make up the underpayment.  If an individual did not pay enough tax by the due date of each of the payment periods, the individual may owe interest even if the individual is due a refund when the return is filed.