Can Your Spouse Challenge a Prenuptial Agreement in an Illinois Divorce?

 Posted on September 08, 2026 in Prenuptial & Postnuptial Agreements

As a couple, you sign a prenuptial agreement to avoid disputes over finances and property in case your marriage ends. If your spouse now wants to challenge that agreement, it leaves you with questions about whether it will still protect you.

Your spouse may be able to challenge a prenup during an Illinois divorce, but Illinois law limits the reasons a court can refuse to enforce a prenup. If your agreement is being challenged in 2026, our Kane County, IL divorce attorneys can review how it was signed and what recourse you have.

When Can a Prenuptial Agreement Be Challenged in Illinois?

Illinois law allows a spouse to challenge a prenup on specific legal grounds. Under 750 ILCS 10/7 of the Illinois Uniform Premarital Agreement Act, the spouse challenging the agreement must prove why it should not be enforced.

One ground is that the spouse did not sign the agreement voluntarily. A prenup can also be challenged if it was unconscionable at the time it was signed and the financial disclosure requirements were not met.

A spouse cannot set aside a prenup simply because its terms are no longer favorable. There must be a legal reason not to enforce the agreement.

What Does It Mean to Sign a Prenup Voluntarily in Illinois?

A voluntary prenup is one that both parties sign of their own free will. A spouse may later challenge an agreement by claiming that pressure or coercion kept them from making a free choice.

The court will look at the circumstances surrounding the signing. This could include how the agreement was presented and what happened before it was signed. The timing is also especially important if the agreement was presented shortly before the wedding.

Having separate attorneys can also provide useful information about how the agreement was negotiated and how much time the person had to review it. However, it's not required for each person to have an attorney for a prenup to be enforceable. The spouse making the challenge must still show that the agreement was not signed voluntarily.

Can Missing Financial Information Affect an Illinois Prenup?

Missing financial information can be part of a successful challenge to a prenup. However, the challenging spouse must show that, at the time of signing, they did not receive fair and reasonable information about the other person's property or debts. The court also considers whether that spouse waived further disclosure in writing or already knew enough about the other person's finances.

Can a Prenup Waive Spousal Maintenance in Illinois?

A prenup can limit or eliminate spousal maintenance, sometimes called alimony. Illinois law provides an exception when enforcing that provision would cause undue hardship because of circumstances the parties could not reasonably have expected when they signed the agreement.

In that situation, a court may order enough support to prevent the hardship. However, a prenup also cannot take away a child's right to support. Child support remains subject to Illinois law even when the parents signed an agreement before marriage.

What Should You Do if Your Spouse Challenges Your Prenup in Illinois?

A challenge does not automatically cancel your prenuptial agreement. Your attorney can review the agreement and the circumstances surrounding its signing.

Gather any records you still have from when the prenup was prepared. Useful documents include:

• Financial disclosures
• Drafts of the prenup
• Written disclosure waivers
• Emails or other messages about signing the agreement

If the prenup covers a business or other valuable property, keep any financial records that were provided before the agreement was signed. Records showing when drafts were exchanged or when each spouse consulted an attorney can also help establish how the process unfolded.

Talk to Our St. Charles, IL Divorce Attorneys About Your Prenuptial Agreement

A contested prenup can affect some of the most important financial issues in an Illinois divorce. Understanding what the agreement covers and whether it can be enforced is an important step before property or support issues are resolved.

The lawyers at Weiler & Associates, P.C. represent clients in Illinois divorces involving prenuptial agreements and complex financial disputes. Attorney Tim Weiler is a Certified Financial Litigator with experience handling difficult financial issues in divorce. Call 630-331-9110 to schedule a consultation with our Kane County, IL divorce lawyers.