Family · Prenuptial agreement
Prenuptial Agreement Requirements in Illinois
What makes a prenuptial agreement valid and enforceable in Illinois: the writing and signature, the voluntariness rule, the financial disclosure each side must give, and what gets a prenup thrown out. Cited to the statute.
What makes a prenuptial agreement valid in Illinois
The writing and signature, voluntariness, and financial disclosure a court looks for before it will enforce a prenup.
Prenuptial agreement enforceability turns on the specific facts and on evolving case law, and Illinois courts scrutinize these agreements closely. Confirm the current text of the Illinois Uniform Premarital Agreement Act, 750 ILCS 10, and recent decisions before relying on this.
| What makes a prenup valid | What it means |
|---|---|
| In writing and signed by both | Under 750 ILCS 10/3, a premarital agreement must be in writing and signed by both parties. It is enforceable without consideration, but an oral premarital agreement does not qualify. |
| Signed voluntarily | Under 750 ILCS 10/7, the agreement must be executed voluntarily. If the challenging party proves it was not signed voluntarily, the agreement is not enforceable. |
| Fair financial disclosure or a written waiver | Before signing, each party should receive a fair and reasonable disclosure of the other’s property and financial obligations, or voluntarily and expressly waive that disclosure in writing, or already have adequate knowledge of the other’s finances. |
| Not unconscionable when executed | The agreement is judged for unconscionability as of the time it was signed. Whether an agreement is unconscionable is decided by the court as a matter of law. |
| What makes a prenup unenforceable | What it means |
|---|---|
| Signed involuntarily | If the party against whom enforcement is sought proves the agreement was not signed voluntarily, it is not enforceable. Being pressured or given no time to review can support that claim. |
| Unconscionable when signed with no disclosure or waiver | The agreement is unenforceable if it was unconscionable when executed and the challenging party was not given a fair disclosure, did not waive disclosure in writing, and could not reasonably have known the other party’s finances. Both parts must be proven. |
| Terms that affect a child’s right to support | Under 750 ILCS 10/8, the right of a child to support is not affected by a premarital agreement. Child support and custody are decided by the court and cannot be fixed in advance by the parents. |
| A support waiver that forces public assistance | If a provision that waives or limits spousal support would leave one party eligible for public assistance at separation or divorce, the court may order support to the extent needed to avoid that result. |
What you can do right now
Concrete, neutral steps to sign a prenup that will hold up in Illinois. This is legal information, not legal advice.
- Put it in writing well before the wedding
Have the agreement drafted in writing and delivered with enough time to read and consider it. Signing right before the wedding invites an involuntariness challenge.
- Exchange full financial disclosure
Both people should exchange a complete and honest list of assets, debts, and income. Keep a record of what was disclosed, or of any written waiver, so the agreement can survive a later challenge.
- Each person should use independent counsel
Illinois does not require it, but each party using a separate lawyer helps show the agreement was voluntary and understood, and reduces the chance a court sets it aside.
A prenuptial agreement decides property and support if a marriage ends, and a court will scrutinize how it was signed. A licensed family-law attorney can draft or review one; the state bar can refer you to one.
→ Illinois State Bar Association, Illinois Lawyer FinderThis is general legal information, not legal advice. Enforceability turns on the exact statute, the case law, and how the agreement was signed, so confirm the current requirements against the statute and talk to a lawyer.
What couples in Illinois get wrong about prenups
Illinois enforces premarital agreements under the Illinois Uniform Premarital Agreement Act, 750 ILCS 10. The agreement must be in writing and signed by both parties under section 3, and it is enforceable without consideration. The enforcement standard in section 7 tracks the Uniform Act: the agreement is not enforceable only if the party challenging it proves either that it was not executed voluntarily, or that it was unconscionable when it was signed and, before signing, that party was not given a fair and reasonable disclosure of the other party’s property and finances, did not expressly waive that disclosure in writing, and could not reasonably have known the other party’s finances. Whether an agreement is unconscionable is decided by the court as a matter of law, judged as of the time of signing. Illinois protects children and the public: under section 8 a child’s right to support is not affected by the agreement, and a court can order spousal support if a waiver would otherwise leave a party eligible for public assistance. This is legal information, not legal advice.
Common questions
Does a prenuptial agreement have to be notarized in Illinois?
The Illinois Uniform Premarital Agreement Act requires the agreement to be in writing and signed by both parties. Notarization is not required by the statute, though couples often notarize the document and use separate lawyers to help show it was voluntary.
Can an Illinois prenup decide child support or custody?
No. Under 750 ILCS 10/8 the right of a child to support is not affected by a premarital agreement. Child support and custody are decided by the court based on the child’s best interest, not by the parents.
What makes a prenuptial agreement unenforceable in Illinois?
It can be thrown out if the challenger proves it was signed involuntarily, or that it was unconscionable when signed and there was no fair disclosure, no written waiver of disclosure, and no adequate knowledge of the other party’s finances.
Do both people need their own lawyer for an Illinois prenup?
Illinois does not require separate lawyers, but each party using independent counsel helps show the agreement was voluntary and understood, which makes it harder to challenge later.
Not legal advicePlainStatute provides plain-language summaries of public law for general information only. This is not legal advice. Statutes change; always confirm current requirements with the official source linked above before acting.