Thanks for asking such a good question.
The answer, as it applies in the jurisdiction where I practice divorce and family law (Utah), is found in Utah Rules of Civil Procedure 60(b)(4):
Rule 60. Relief from judgment or order.
(b) Mistakes; inadvertence; excusable neglect; newly discovered evidence; fraud, etc. On motion and upon just terms, the court may relieve a party or its legal representative from a judgment, order, or proceeding for the following reasons:
(b)(4) the judgment is void[.]
(c) Timing and effect of the motion. A motion under paragraph (b) must be filed within a reasonable time and for reasons in paragraph (b)(1), (2), or (3), not more than 90 days after entry of the judgment or order or, if there is no judgment or order, from the date of the proceeding. The motion does not affect the finality of a judgment or suspend its operation.
There are other ways to obtain relief from a judgment under Rule 60(b) when the basis for seeking relief from the judgment is other than the judgment being void, and rule 60 itself acknowledges:
(d) Other power to grant relief. This rule does not limit the power of a court to entertain an independent action to relieve a party from a judgment, order or proceeding or to set aside a judgment for fraud upon the court. The procedure for obtaining any relief from a judgment shall be by motion as prescribed in these rules or by an independent action.
Utah Family Law, LC | divorceutah.com | 801-466-9277
(80) Eric Johnson’s answer to Do you have any experience on how to challenge a void judgment in a family court? – Quora