Are prenuptial agreements enforceable in Illinois?

Illinois follows the UPAA with its standard conjunctive test, plus one important escape valve for spousal support.

1. Governing Statute

Illinois Uniform Premarital Agreement Act, 750 ILCS 10/1–10/11 (adopted 1990). Postnuptial agreements are governed by separate common law principles.

2. Formality Requirements

The agreement must be in writing and signed by both parties (750 ILCS 10/3). Marriage is the consideration; the agreement is effective upon marriage (750 ILCS 10/4).

3. Voluntariness

Under 750 ILCS 10/7(a)(1), the challenger must prove the agreement was not executed voluntarily. Illinois courts examine the totality of circumstances — counsel access, time to review, sophistication, emotional pressure. In re Marriage of Barnes, 324 Ill. App. 3d 514 (2001), illustrates the high bar for proving involuntariness.

4. Disclosure

Under 750 ILCS 10/7(a)(2), the agreement is unenforceable if unconscionable when executed AND, before execution, the party (i) was not provided fair and reasonable disclosure, (ii) did not voluntarily and expressly waive disclosure in writing, and (iii) did not have or reasonably could have adequate knowledge of the other's property and obligations.

5. Unconscionability

Unconscionability is determined as of execution and is a question of law (750 ILCS 10/7(c)). Disparity alone is insufficient.

6. What Cannot Be Waived

Child support cannot be adversely affected (750 ILCS 10/4(b)). Spousal maintenance escape clause: under 750 ILCS 10/7(b), if a spousal-maintenance waiver causes one party to be eligible for public assistance at separation/divorce, a court may require the other to provide support sufficient to avoid that eligibility — even over the waiver.

7. Key Illinois Case Law

In re Marriage of Barnes (2001) (voluntariness); In re Marriage of Murphy, 359 Ill. App. 3d 289 (2005) (disclosure adequacy); In re Marriage of Drag, 326 Ill. App. 3d 1051 (2002) (unconscionability standard).

This is legal information, not legal advice.