Due dates

—(1) If the last day for performing an act prescribed by tax legislation falls on a day on which the Department is not open to the public for business, the act is considered timely if it is performed on the next succeeding day on which the Department is open for business. Tax Administration and Procedure CAP. 51 23 (2) A declaration, appeal, or other document, other than a payment, is considered filed on the date it is stamped as received by the Department or, in the case of filing by mail, on the date of the postmark.