Va. Code § 58.1-1717
The clerk of the court wherein the probate or administration tax has been paid by an estate shall thereafter compare the total value of the probate estate as shown on the probate tax return with the total value shown on the inventory of such estate to determine whether the estate has been undervalued for tax purposes. If such clerk finds that such estate has been undervalued, he shall thereupon collect such additional tax as may be due. In the event of an overpayment of such tax, the personal representative may apply to the Department of Taxation and, if a local probate tax was paid, to the treasurer of the city or county for a refund. No additional tax shall be payable or no refund made if the payment or refund due would be less than twenty-five dollars.
Va. Code § 58.1-1717