(a) Default order not final. In order to prevent injustice or for good cause shown, and on such conditions as may be appropriate, a non-final default order (including any award therein) may be set aside by the official who issued the order.

(1) Procedure for setting aside non-final default order. Any party or person who is the subject of a default order issued pursuant to these rules may, at any time before the order becomes final pursuant to § 12.22(c), file and serve a motion to set aside the default, which shall set forth reasons why the act or omission for which the party was defaulted was not willful, why there is a reasonable likelihood of success for the party's claim or defense if heard on the merits, and why no prejudice will be sustained by other parties if the default is set aside. A motion to set aside a default order filed pursuant to this paragraph (a)(1) shall be decided, in the first instance, by the official who issued the default order.

(2) Review. A denial of a motion to set aside a non-final default order by the official who issued the order shall be treated as an initial decision, which may be appealed to the Commission in accordance with the requirements of § 12.401 of these rules. A grant of a motion to set aside a non-final default order may be appealed only in accordance with the requirements of § 12.309 of these rules.

(b) Default order final. A default order that has become final pursuant to § 12.22(c) shall not be set aside except upon a motion filed and served by the defaulted party showing that the defaulted party should be relieved from the default order because of fraud perpetrated on a decisionmaking official or the Commission, mistake, excusable neglect, or because the order is void for want of jurisdiction. Such a motion shall also show that, if the default order were set aside, there would be a reasonable likelihood of success for the defaulted party's claim or defense on the merits and that no party would be prejudiced thereby. Motions to set aside a final default order for fraud, mistake, or excusable neglect shall be filed within one year after the order was issued. All motions to set aside default orders shall be decided, in the first instance, by the official who issued the order. A denial of a motion to set aside a default order that has become final shall be treated as an initial decision, which may be appealed to the Commission in accordance with the requirements of § 12.401. A grant of a motion to set aside a final default order shall be treated as a nonfinal order which may be appealed only in accordance with the requirements of § 12.309.