North Carolina Administrative Code Title 17 — Revenue
17 NCAC 06D .0208 — Overpayments
An overpayment for any period occurs when the withholding and estimated tax payments are more than the total of any underpayments for an earlier period plus the lesser of the required installment or the annualized income installment for the period. If there is an overpayment for a period, it shall be carried to the next period and added to the withholding and estimated tax paid for that later period to determine any underpayment or overpayment for that later period.
Source: official text