Key takeaways:
- In Illinois, a prenup must be in writing and signed by both of you. It takes effect when you marry (750 ILCS 10/3 and 10/5).
- A court can refuse to enforce it if one of you didn’t sign voluntarily, or if it was unconscionable and there was no fair disclosure of finances (750 ILCS 10/7).
- A prenup cannot reduce child support. A waiver of spousal support can be overridden if it would cause undue hardship.
- Illinois law does not require separate lawyers. Many couples still each hire one, because independent advice makes it harder to argue later that someone didn’t understand what they signed.
Last reviewed: October 22, 2026. This article is general information about Illinois law, not legal advice. Laws change and every situation is different, so talk to a licensed Illinois attorney about your own case.
Thinking about a prenuptial agreement before getting married in Rockford? You are not being unromantic. You are deciding together, while you still get along, what happens to your money and property if the marriage ends. This guide explains what Illinois law actually requires, what can make a prenup fall apart, and how to find qualified help in Winnebago County.
Contents
- What Illinois requires for a valid prenup
- What can make a prenup unenforceable
- What a prenup can and can’t cover
- Do you each need a lawyer?
- Finding help in Rockford
- FAQ
What Illinois requires for a valid prenup
Illinois follows the Illinois Uniform Premarital Agreement Act (750 ILCS 10), which applies to agreements signed on or after January 1, 1990. The core rules are short:
- In writing, signed by both. An oral agreement is not a prenup (10/3).
- Effective on marriage. The agreement only becomes effective once you are married (10/5).
- Changes need a signed writing. After the wedding, you can amend or revoke the agreement only by a written agreement signed by both spouses (10/6).
The law does not require a notary, a waiting period or a specific form. In practice, signing well before the wedding and keeping a record of the financial disclosure you exchanged makes the agreement much harder to attack later.
What can make a prenup unenforceable
Under 750 ILCS 10/7(a), a prenup is not enforceable if the spouse challenging it proves either:
- they did not sign it voluntarily, or
- it was unconscionable when signed and, before signing, they did not receive fair and reasonable disclosure of the other’s property and debts, did not voluntarily waive that disclosure in writing, and did not have (and could not reasonably have had) adequate knowledge of those finances.
Whether an agreement is unconscionable is decided by the judge, as a matter of law (10/7(c)).
Looking at those rules, the weak points are clear: pressure close to the wedding date, incomplete financial disclosure and terms one spouse did not understand. Full, written disclosure on both sides addresses the disclosure test directly.
What a prenup can and can’t cover
Usually allowed
- Who owns property each of you brings into the marriage, and property acquired during it
- How property is divided if you divorce or one of you dies
- Rights to buy, sell, use or manage property
- Spousal support (maintenance), subject to the hardship rule below
- Life insurance and wills needed to carry out the agreement
Not allowed
- Anything that adversely affects a child’s right to support (10/4(b))
- Terms that violate public policy or criminal law
- Custody (parenting time and decision-making) decisions, which courts make based on the child’s best interests at the time
Spousal support waivers: if a prenup modifies or eliminates maintenance and that causes one spouse undue hardship because of circumstances not reasonably foreseeable when it was signed, the court can still order support despite the agreement (10/7(b)).
Without a prenup, Illinois courts divide marital property under 750 ILCS 5/503 in “just proportions”, which is not necessarily 50/50. Property owned before the marriage, gifts and inheritances are generally non-marital, but they can lose that status if they are mixed with marital assets. A prenup lets you set those rules yourselves instead.
Do you each need a lawyer?
No Illinois statute requires each spouse to have a separate attorney. Independent legal advice is one of the factors a court may look at when deciding whether an agreement was signed voluntarily and with understanding, though it doesn’t decide the question on its own. Under the lawyers’ professional conduct rules, one attorney generally can’t advise both partners on the same prenup, because their interests conflict.
Before a first consultation, gather:
- A list of your assets and debts, with approximate values (accounts, real estate, retirement plans, business interests, loans)
- Recent tax returns and pay stubs
- Any expected inheritance or family business you want to protect
- Your wedding date, so the agreement can be signed well in advance
- Questions about fees: flat fee or hourly, and what the review of a draft from your partner’s lawyer will cost
Finding help in Rockford
We do not recommend or rank specific law firms. To find a licensed family law attorney in the Rockford area:
- Check the license: confirm that any lawyer is licensed and in good standing with the Illinois Attorney Registration and Disciplinary Commission (ARDC).
- Ask about family law focus: prenups are usually handled by family law or estate planning attorneys. Ask how many premarital agreements they draft or review each year.
- Illinois Legal Aid Online: free plain-language guides and forms.
- Winnebago County Courthouse Self-Help Center: Room 304 (in the law library), 400 West State Street, Rockford, IL 61101, 815-319-4526. The court lists a temporary entrance at 403 Elm Street, one block south, so check before you go. Staff can help with forms and procedures but cannot give legal advice.
Related guides
FAQ
Can we sign a prenup after the wedding?
Not as a prenup. An agreement signed after marriage is a postnuptial agreement, which Illinois courts review under general contract principles rather than the Premarital Agreement Act. An Illinois attorney can explain how that differs for your situation.
How close to the wedding is too close?
Illinois sets no deadline. But signing days before the ceremony invites a claim that it was not voluntary. Many couples aim to sign weeks or months ahead.
Can a prenup decide who gets the kids?
No. Parenting time and decision-making are decided by the court based on the child’s best interests, and child support cannot be reduced by a prenup.
Can we change the prenup later?
Yes, but only through a written agreement signed by both spouses (750 ILCS 10/6).
Sources: Illinois Uniform Premarital Agreement Act, 750 ILCS 10; 750 ILCS 5/503; Winnebago County Circuit Court (17th Judicial Circuit).
