Home › Family & estate planning › Prenuptial agreements

Prenuptial agreements under Illinois lawPrenuptial agreements

Wang Law Firm, LLC · David Wang, Managing Attorney · Attorney-reviewed · Updated October 2026

Start here: (1) In Illinois, a prenuptial agreement must be in writing and signed by both parties, and it takes effect only upon marriage. (2) The agreement cannot adversely affect a child’s right to support. (3) An agreement signed under coercion, or one that is unconscionable and was not preceded by adequate financial disclosure, may not be enforced. (4) Presenting the agreement only a few days before the wedding leaves room for a later claim that it was “not voluntary”; start early. (5) Most courts hold that a “mutual waiver of support” clause in a prenuptial agreement does not release the I-864 Affidavit of Support obligation.

A prenuptial agreement (called a premarital agreement under Illinois law) is a written agreement that two people planning to marry sign in advance to set out how property will be handled during the marriage, on divorce, or on the death of a spouse. It is often used to clarify who owns premarital property, income earned during the marriage, real estate and company equity, reducing uncertainty if a dispute arises later.

In the United States, signing a prenuptial agreement is not unusual and does not mean the parties distrust each other. For international marriages and immigrant families, it can also spell out property in China, assets given by family, and future inheritance arrangements. But a prenuptial agreement is a contract with strict legal requirements, and if it is poorly drafted it may not be enforced when it is actually needed. This page focuses on Illinois law and briefly explains the differences in New York and Massachusetts.

Illinois: the Uniform Premarital Agreement Act (750 ILCS 10)

Illinois has adopted the Illinois Uniform Premarital Agreement Act (750 ILCS 10). The core rules are as follows:

Issue	Rule	Provision
Definition	An agreement between prospective spouses made in contemplation of marriage and effective on marriage; “property” includes income and earnings	750 ILCS 10/2
Formalities	Must be in writing and signed by both parties; no consideration is required	750 ILCS 10/3
Effective date	Becomes effective on marriage and has no effect before marriage	750 ILCS 10/5
Amendment and revocation	After marriage, may be amended or revoked only by a written agreement signed by both parties, again without consideration	750 ILCS 10/6
When not enforced	Not signed voluntarily; or unconscionable when signed, and before signing the party was not provided fair and reasonable financial disclosure, did not expressly waive disclosure in writing, and did not have and could not reasonably have had knowledge of the other party’s finances	750 ILCS 10/7(a)
Protection for maintenance	If a provision modifying or eliminating spousal maintenance causes one party undue hardship because of circumstances not reasonably foreseeable when the agreement was signed, the court may, notwithstanding the agreement, award the maintenance necessary to avoid the hardship	750 ILCS 10/7(b)
If the marriage is void	If the marriage is declared invalid, the agreement is enforceable only to the extent necessary to avoid an inequitable result	750 ILCS 10/8
Limitations	The statute of limitations for claims under the agreement is tolled during the marriage; equitable defenses such as laches and estoppel remain available	750 ILCS 10/9

Whether an agreement is unconscionable is decided by the court as a matter of law (750 ILCS 10/7(c)). Note that the second situation in section 7(a) requires unconscionability and the lack of disclosure (among other conditions) to be present together, which is why full, written financial disclosure is the most important step in protecting the agreement’s validity.

What can and cannot be agreed

What may be covered (750 ILCS 10/4(a))

The parties’ rights and obligations in any property, whenever and wherever acquired;
The right to buy, sell, use, transfer, give away, mortgage, manage and control property;
How property will be disposed of on separation, divorce, death or the occurrence of other events;
Modification or elimination of spousal maintenance, subject to section 7(b);
Making a will, trust or other arrangement to carry out the agreement;
Ownership of the death benefit from a life insurance policy;
The law governing the construction of the agreement (choice of law);
Any other matter, including personal rights and obligations, that does not violate public policy or a criminal statute.

What cannot be agreed or will not be enforced

Child support: A child’s right to support may not be adversely affected by the agreement (750 ILCS 10/4(b)). The parties cannot agree in advance that “no child support will be paid after divorce” or reduce child support; child support is decided by the court under state law and in the child’s interests.
Allocation of parental responsibilities: Who cares for the children and how decisions are made is decided by the court according to the children’s best interests; terms in a prenuptial agreement generally do not bind the court.
Terms that violate public policy or criminal law: for example, clauses that encourage divorce or are conditioned on illegal conduct.
Obligations to third parties or the government: for example, the I-864 support obligation, discussed below.

When and how to sign

Start early: The law does not say the agreement must be signed a certain number of days before the wedding, but the closer to the wedding and the greater the pressure, the easier it is to claim the agreement was “not signed voluntarily.” We generally recommend starting negotiations as soon as the wedding date is set, leaving both parties time to read, ask questions and make changes.
Full financial disclosure: List each party’s assets, liabilities and income in schedules attached to the agreement, including real estate, deposits, equity, loans and guarantees in China and other countries. Values can be stated as approximate amounts with an explanation of the basis.
Separate, independent lawyers: Illinois law does not require both parties to have lawyers, but their interests are opposed, and review and explanation by each party’s own lawyer helps show that the agreement was signed voluntarily and with full understanding. We represent only one party and will not represent both.
Language: If one party is not fluent in English, make sure that party truly understands the agreement. Consider providing a checked Chinese translation, having a Chinese-speaking lawyer explain it, and stating in the agreement which language version controls.
Execution formalities: Illinois law requires only a writing signed by both parties. But if the agreement may later be used in a state with additional formal requirements, such as New York, or in another country, we recommend having it acknowledged before a notary as well.

Main differences in New York and Massachusetts

State	Legal basis	Key points
Illinois	Uniform Premarital Agreement Act (750 ILCS 10)	In writing and signed by both parties; not enforced if involuntary or if “unconscionable + lack of disclosure”; child support may not be adversely affected
New York	Domestic Relations Law §236(B)(3)	An agreement made before or during the marriage must be in writing, subscribed by the parties, and acknowledged in the manner required for a deed to be recorded. In Matisoff v. Dobi (1997), New York’s highest court (the Court of Appeals) held that an unacknowledged marital agreement is unenforceable in a matrimonial action, even where both parties admit the signatures are genuine. Terms on spousal maintenance are also reviewed for whether they were fair and reasonable when made and are not unconscionable at the time of judgment; terms concerning child support must comply with the requirements of New York’s child support standards.
Massachusetts	Case law (e.g., DeMatteo v. DeMatteo, 2002)	Massachusetts has not adopted the Uniform Premarital Agreement Act. The court first examines whether there was full disclosure at signing, whether the other party waived rights knowingly, and whether the terms were fair and reasonable; the fact that an agreement is clearly unfavorable to one party does not by itself make it invalid. At enforcement, the court also takes a “second look”: the agreement may be denied enforcement only if circumstances changed during the marriage such that enforcing it would leave a party without sufficient property, maintenance or appropriate employment for support.

If the parties may later move to another state or return to their home country, the agreement can specify the governing law, but whether courts in another state or country will respect that choice depends on local rules.

Prenuptial agreements and the I-864 Affidavit of Support

When a U.S. citizen or green card holder petitions for a marriage-based green card for a foreign spouse, the petitioner usually must sign the I-864 Affidavit of Support, promising to maintain the sponsored immigrant’s income at 125% of the federal poverty guidelines during the sponsorship period. The obligation generally continues until the sponsored immigrant naturalizes, has worked 40 quarters in the U.S. (in some cases a spouse’s quarters can be credited), loses permanent resident status and departs the U.S., or either the sponsor or the sponsored immigrant dies. Divorce does not end the obligation.

Can a clause in a prenuptial agreement stating that “neither party will seek support from the other after divorce” release the I-864 obligation? Most published decisions to date say no:

Erler v. Erler, 824 F.3d 1173 (9th Cir. 2016): The parties’ prenuptial agreement waived support by either party. The court held that neither the divorce judgment nor the prenuptial agreement terminated the I-864 obligation, because that right arises under federal law and is independent of rights under state divorce law.
Shah v. Shah (D.N.J. 2014): The court held that the wording of the prenuptial agreement in that case did not expressly address rights under the I-864 and was not enough to release the sponsor’s obligation.
Toure-Davis v. Davis (D. Md. 2014): The prenuptial agreement was signed first and the I-864 later; the court held that neither the prenuptial agreement nor the later separation agreement terminated the I-864 obligation.
Some decisions reach a different result. For example, in Blain v. Herrell (D. Haw. 2010), the court declined to grant the sponsored immigrant’s support claim under the I-864 on the basis of the parties’ valid prenuptial agreement.

In addition, the Seventh Circuit, which includes Illinois, held in Liu v. Mund (2012) that a sponsored immigrant has no duty to seek employment to reduce the sponsor’s liability. Overall: do not count on a prenuptial agreement to exclude the I-864 obligation. Before signing the I-864, a sponsor should understand that it is an independent promise to the U.S. government; how the agreement addresses I-864-related issues must be designed separately for the parties’ circumstances, accepting that its effect is uncertain.

Also, signing a prenuptial agreement does not by itself show that a marriage is not genuine. Marriage-based immigration review looks at whether the parties intended to establish a life together when they married, and a prenuptial agreement is usually just one part of their property arrangements.

International marriages and assets in China

List property in China: Real estate, deposits, investment products, equity, loans made to others and guarantees should all be included in the financial disclosure schedules, with the date and source of acquisition (purchased before marriage, gift from parents, inheritance, etc.).
Family gifts and inheritances: The agreement can provide that property received by gift from parents or by inheritance, and its appreciation, remains separate, and can address how income from that property is handled.
Translation: Chinese-language title documents and bank records attached as exhibits should be accompanied by English translations. For later use in a U.S. court, translations usually need a translator’s certification.
Validity in China: Whether a prenuptial agreement signed in the U.S. will be recognized by a Chinese court, whether it can be used for real estate registration in China, and what notarization and authentication it needs are questions for a lawyer licensed in China. We do not give opinions on Chinese law. Where necessary, consider making separate arrangements in each country.
Governing law and forum: Where the parties may live in the future and where a divorce may be filed both affect how the agreement works. Before signing, list the possible scenarios and discuss them.

Postnuptial agreements

A married couple can also sign a postnuptial agreement addressing ownership of property and how it will be handled on divorce. The Illinois Uniform Premarital Agreement Act applies only to premarital agreements; Illinois has no specific statute on postnuptial agreements, and courts generally review them under contract principles, focusing on voluntariness, full disclosure and fairness of the terms. Because the parties are already married when they sign, postnuptial agreements may receive stricter scrutiny. 750 ILCS 5/503(a)(4) lists “property excluded by valid agreement of the parties” (including a prenuptial or postnuptial agreement) as non-marital property, showing that Illinois recognizes qualifying postnuptial agreements.

In Ansin v. Craven-Ansin (2010), the Massachusetts Supreme Judicial Court (SJC) recognized that postnuptial agreements can be enforced, but required careful scrutiny: each party had the opportunity to obtain independent counsel, there was no fraud or coercion, all assets were fully disclosed before signing, each party knowingly and explicitly agreed in writing to waive the right to a judicial equitable division of property, and the agreement was fair and reasonable both when signed and at the time of divorce. In New York, postnuptial agreements must likewise meet the formal requirements of DRL §236(B)(3) (Matisoff v. Dobi itself involved an unacknowledged postnuptial agreement).

Common situations for signing a postnuptial agreement include: one spouse starting a business or receiving company equity, inheriting or receiving a large family gift, preparing to move to another state or country, or not having had time to sign a prenuptial agreement before the wedding.

How we can help

Represent your side in drafting or reviewing a prenuptial or postnuptial agreement under Illinois, New York or Massachusetts law, explaining it clause by clause in Chinese if you prefer;
Help prepare the financial disclosure schedules, including assets in China and other countries;
Explain I-864 and other immigration-related obligations in light of the marriage-based immigration timeline, so that the agreement and the immigration documents do not contradict each other;
Arrange signing and notarization, and work with your lawyer in China on China-side issues.

Frequently asked questions

Does a prenuptial agreement have to be notarized?

The Illinois Uniform Premarital Agreement Act requires only a writing signed by both parties. But New York requires acknowledgment in the manner required for recording a deed, or the agreement is unenforceable in a divorce action, and the agreement may later be used in another state or country. To be safe, we generally recommend notarization.

If we sign only a week before the wedding, is the agreement invalid?

Not necessarily, but the risk is higher. The closer the signing is to the wedding, the easier it is to claim “I was under pressure and did not sign voluntarily.” The court looks at all the circumstances, including whether there was time to consult a lawyer and whether the party knew well in advance that an agreement would be signed. It is best to start early.

Can a prenuptial agreement decide who the children live with after a divorce and how much child support is paid?

Illinois law provides that a child’s right to support may not be adversely affected by a prenuptial agreement, and arrangements for the children’s care are decided by the court according to their best interests. The agreement can express the parties’ shared understanding, but it does not bind the court and cannot reduce the support a child is entitled to.

I am a U.S. citizen sponsoring my foreign fiancée for a green card. If we sign a prenuptial agreement, am I still bound by the I-864?

Yes. Most courts hold that a prenuptial agreement does not release the I-864 obligation, and divorce does not end it either. Before signing the I-864, you should understand that it is a promise to the U.S. government; the obligation generally lasts until the other party naturalizes, has worked 40 quarters, loses permanent resident status and departs the U.S., or either party dies.

What happens if I do not disclose my property in China?

Under Illinois law, if the agreement is found unconscionable when signed, and a party was not given fair and reasonable financial disclosure beforehand, did not waive disclosure in writing, and could not reasonably have known the other party’s finances, the agreement may not be enforced. Incomplete disclosure gives the other party grounds to challenge the agreement later.

Can we change the prenuptial agreement after we are married?

Yes. Illinois law provides that after marriage a prenuptial agreement may be amended or revoked by a written agreement signed by both parties, without consideration. Voluntariness and disclosure still matter when making changes.