It depends on the time frame. If the divorce was entered in the last 30 days, you can file a Motion To Vacate under section 2-1301. Under this section the court can vacate “set aside any final order or judgment upon any terms and conditions that shall be reasonable.” This is a very easy standard to satisfy. If the assets were concealed, the court is likely to vacate the divorce and you’ll start from scratch.
If it’s been more than 30 days since the entry of the divorce, you can file a Motion to Vacate under Section 2-1401. The case, In Re Marriage of Benjamin and Benjamin 2017 IL App (1st) 161862, goes into the requirements at length:
“Section 2-1401 provides a mechanism by which a party may obtain relief from a final judgment when 30 days or more have passed since its entry. The purpose of the statute is to allow a party to alert the court to facts that, if known at the time, would have precluded judgment from being entered. A proceeding pursuant to section 2-1401 does not provide the litigant a new opportunity to perform a task that should have been completed early in the proceeding, nor does it allow a litigant relief from the consequences of his mistake or negligence.
In order to be entitled to relief pursuant to section 2-1401, a party must set forth specific factual allegations to establish (1) the existence of a meritorious claim, (2) due diligence in presenting the claim to the trial court in the original action, and (3) due diligence in filing the section 2-1401 petition. When a petition is based on a claim of newly discovered evidence, it must be shown that the evidence was not known at the time of the original proceeding and “could not have been discovered by the petitioner with the exercise of reasonable diligence.” A petitioner bears the burden of establishing a right to relief.
Normally, a section 2-1401 claim must be brought within two years after the entry of the order of judgment, however, a petition may be brought after more than two years if the moving party alleges fraudulent concealment. In order to establish fraudulent concealment, “the petitioner must prove by clear and convincing evidence that the respondent intentionally misstated or concealed a material fact that the respondent had a duty to disclose and that the petitioner detrimentally relied on the respondent’s statement or conduct. When a trial court holds an evidentiary hearing, like the trial court did here, the decision to grant or deny relief is within the sound discretion of the trial court.”
Therefore, you may try to re-open the case within two years if you meet the 3 requirements. If it’s been more than two years, you have to meet the 3 requirements and establish fraudulent concealment.
Again, In Re Marriage of Benjamin and Benjamin guides us as to what fraudulent concealment is and isn’t.
“Illinois law has long held that a party cannot assert fraudulent concealment where the party did or should have discovered the conduct through ordinary diligence and still had a reasonable amount of time to present the claim…. More specifically, “a settlement agreement will be set aside only if the misrepresentation of the assets could not reasonably have been discovered at the time of, or prior to, the entry of the judgment, and a litigant will not be relieved of the consequences of her lack of diligence in failing to discover such information relevant to the dissolution proceeding.”
Therefore, two years after the entry of the divorce, you must prove that you asked for information about the assets, you did so in a diligent way (usually issuing subpoenas), and the opposing party still concealed the assets.