What Is a Postnuptial Agreement in Illinois?

A postnuptial agreement is a contract between two married people where they address what will happen to their property in the event of a divorce. Postnuptial agreements are very similar to prenuptial agreements with the major difference that they are entered into after the parties are married rather than before.

Some of the matters that may be addressed in postnuptial agreements are:

• The division of debts should the parties divorce
• How property, or assets, will be divided in case of divorce
• If/how monetary support will be provided in case of divorce

As long as the provisions are compliant with the laws of your state, most marital issues may be addressed.

⚖️ At a Glance
When a postnup holds up — and when it doesn't
Illinois scrutinizes postnups closely. These factors decide enforceability.
What it CAN do
• ✓In writing and signed by both spouses
• ✓Entered voluntarily — no pressure or threats
• ✓Backed by full, fair financial disclosure
• ✓Terms that aren't unconscionable
• ✓A real chance for independent legal advice
What it CAN'T do
• ✕Signed under coercion or duress
• ✕Assets hidden or understated
• ✕Grossly one-sided terms
• ✕Sprung at the last minute with no review
• ✕Any attempt to set child support or custody

Do Postnups Hold Up in Court?

If the agreement is fair in its terms, abides by local laws, and both spouses entered into it voluntarily, the court will usually uphold a postnuptial agreement. Still, courts tend to look down on postnuptial agreements. When contracts are entered into, it is typically because two parties are bargaining over something, such as a piece of land. If one party does not agree to the terms, they have the ability to walk away from the agreement. With postnuptial agreements, the parties are already married, so there really is no bargaining power.

🛡️ Stress-Test It
Will your postnup hold up? Stress-test it
Tap each safeguard your agreement can honestly claim — gaps are where postnups get thrown out.
• Both spouses signed a written agreement
• Each signed voluntarily, without pressure or threats
• Both fully disclosed their assets and debts
• The terms aren't grossly one-sided
• Each had a real chance at independent counsel
A postnup only holds up if it’s fair, disclosed, and freely signed.

Who Needs a Postnuptial Agreement in Illinois?

A postnuptial agreement is recommended for many situations, but it is especially important in the following scenarios.

Business Owners. If you own a business and want to protect its earnings, even those that have occurred during the time of the marriage, a postnuptial agreement can help.

Fear of Financial Talks. If you and your spouse were worried about discussing finances prior to your wedding day but now that you are married, you see how a mutual agreement could be beneficial, a postnuptial agreement may be the route for you.

Inheritance. If you or your spouse has received an inheritance that you don't want to be considered a joint asset, a postnuptial agreement can help keep it separate in case of divorce. Also, if you begin to see that there may be inheritance disputes between the children you each had in previous relationships, a postnuptial agreement can prevent that from happening.

👥 Who Needs One
When people turn to a postnup
Circumstances change after the wedding — a postnup catches up.
A business took off
One spouse's company grew significantly after the wedding.
An inheritance arrived
A spouse received money or property they want to keep separate.
Rebuilding trust
Couples use one to reset expectations after a difficult period.
A blended family
Protecting children from a prior relationship.

Do You Need a Family Law Lawyer in Illinois for a Postnup?

In short, yes, you should have an attorney to represent you in a postnuptial agreement for several reasons:

• To be sure you are treated fairly in the agreement
• To have the agreement upheld, as a court is much more likely to say it is a valid contract if both parties were represented by counsel when they entered into it
• To be sure the terms of the agreement are something the laws in your state allow

Remember, when you hire an attorney, their job is to look out for your best interests.

Considering a postnup?

Circumstances change. A well-built postnup brings clarity — we'll make sure it holds up.

Request a Consultation

$100 consultation · you'll be directed to schedule & pay · 312-380-1070

Keep reading

Prenuptial Agreements in Illinois→High-Asset & Complex Property Division in Illinois→The Illinois Divorce Process, Step by Step→


Erik B. Diggs · Founding Attorney

Erik B. Diggs is the Founding Attorney of The Diggs Law Firm, a Chicago family law firm that focuses on contested divorce, property division, and parenting matters. He is admitted to practice law in Illinois and serves clients throughout Cook County and the surrounding area from 77 W Wacker Drive, Suite 4500, Chicago, IL 60601. Call 312-380-1070.

Disclaimer: This article is provided for general informational and educational purposes only and describes Illinois law in general terms; any interactive tools are illustrative estimates, not legal advice or a prediction of any outcome. Reading it does not create an attorney-client relationship. Because every family law matter turns on its own facts, you should consult a licensed Illinois attorney before acting on anything here. The Diggs Law Firm · 77 W Wacker Drive, Suite 4500, Chicago, IL 60601 · 312-380-1070. Attorney advertising.