Illinois: Prenuptial Agreement Requirements

Requirements one by one

Illinois uses its enactment of the UPAA

The Illinois Uniform Premarital Agreement Act, 750 ILCS 10/1-11, supplies the
formation, subject-matter, enforcement, support, and post-marriage change rules
for agreements executed on or after January 1, 1990.

Both parties must sign a writing

Section 10/3 requires the agreement to be in writing and signed by both
parties. No additional consideration is needed. Sections 10/2 and 10/5 make the
agreement effective when the contemplated marriage occurs.

The Act does not add a notary or witness step

The formalities section requires the signed writing but no notarization,
acknowledgment, witnesses, attestation, oath, or recording. A form's notary
block is therefore not an additional statutory validity requirement under
§ 10/3.

Disclosure matters only within the combined unconscionability route

Under § 10/7(a)(2), the party resisting enforcement must first show that the
agreement was unconscionable when executed and also establish all three
disclosure subparts: no fair and reasonable disclosure, no voluntary and
express written waiver, and no adequate knowledge that the party had or
reasonably could have had.

The statute joins those requirements. A disclosure problem alone is not the
complete § 10/7(a)(2) challenge, and a waiver must be express, voluntary, and
written.

No counsel mandate or fixed review period appears in the Act

The Act does not require independent counsel, a counsel-waiver document, a
minimum final-draft review period, or a fixed number of days before the wedding.
Voluntary execution remains separately required under § 10/7(a)(1).

Unconscionability is measured at execution

Section 10/7(a) makes involuntary execution one independent defense. Its other
route requires execution-time unconscionability plus the complete disclosure
failure. Subsection (c) assigns the unconscionability issue to the court as a
matter of law.

A support waiver has an unforeseen-hardship safety valve

Section 10/4(a)(4) permits modification or elimination of spousal support. But
§ 10/7(b) lets the court require support to the extent necessary to prevent
undue hardship when the hardship results from circumstances that were not
reasonably foreseeable when the agreement was executed.

That is not a public-assistance-only test. The statute uses undue hardship and
unforeseeable circumstances as its stated conditions.

Child support and parental responsibilities remain protected

Section 10/4(b) flatly states that a child's support right may not be adversely
affected. Section 10/4(a)(8) also bars personal-rights terms that violate public
policy or a criminal-penalty statute. For parental decision-making, 750 ILCS
5/602.5 directs the court to allocate responsibilities according to the child's
best interests.

Amendment or revocation repeats the signed-writing rule

After marriage, § 10/6 allows amendment or revocation only through a written
agreement signed by both parties. The changed agreement or revocation needs no
consideration, and the section adds no notarization requirement.

What trips people up

• The unconscionability and disclosure elements are cumulative. Section
  10/7(a)(2) does not make any single missing disclosure item an automatic
  invalidity rule.
• The support exception is not limited to public benefits. It asks whether
  unforeseen circumstances would cause undue hardship and authorizes only the
  support necessary to avoid that hardship.
• Notarization is not part of the statutory amendment rule. Section 10/6
  requires a writing signed by both parties, without a notary condition.

Common questions

Does an Illinois prenup need consideration beyond the marriage?

No. Section 10/3 says the original agreement is enforceable without
consideration, and § 10/6 says the same for an amendment or revocation.

Does Illinois require signing seven days before the wedding?

No fixed pre-wedding period appears in the Act. The agreement must be signed
before it becomes effective upon marriage, and execution must be voluntary.

Can the agreement waive every future support claim no matter what happens?

Not conclusively. Section 10/7(b) preserves a narrow court safety valve for
undue hardship caused by circumstances not reasonably foreseeable at
execution.

Statutes and sources

• 750 ILCS 10/2 — premarital-agreement and property definitions. Official
  Illinois statute
  (accessed 2026-07-27).
• 750 ILCS 10/3 — writing, both signatures, and no-consideration rule.
  Official Illinois statute
  (accessed 2026-07-27).
• 750 ILCS 10/4 — permitted subjects, support modification, public-policy
  limit, and child-support protection. Official Illinois
  statute
  (accessed 2026-07-27).
• 750 ILCS 10/5 — effect upon marriage. Official Illinois
  statute
  (accessed 2026-07-27).
• 750 ILCS 10/6 — signed-writing amendment and revocation route. Official
  Illinois statute
  (accessed 2026-07-27).
• 750 ILCS 10/7 — voluntariness, unconscionability, disclosure, and support-
  hardship rules. Official Illinois
  statute
  (accessed 2026-07-27).
• 750 ILCS 5/602.5 — child-best-interest allocation of parental decision-
  making responsibilities. Official Illinois
  statute
  (accessed 2026-07-27).