Washington: Prenuptial Agreement Requirements

Requirements one by one

Washington uses a writing statute plus case law

Washington has not adopted the UPAA or UPMAA. RCW 19.36.010 supplies the
statute-of-frauds form rule for an agreement made upon consideration of
marriage. Bernard and Matson provide the controlling two-prong fairness test.

RCW 26.16.120 is not the ordinary divorce-focused prenup statute. It concerns
an agreement jointly made by people who are already spouses or domestic
partners about community property, to take effect on death. Its deed-style
formalities should not be imported into every premarital agreement.

The agreement must be written and signed by the charged party

RCW 19.36.010 makes a marriage-consideration agreement void unless the
agreement or a memorandum is written and signed by the party to be charged.
That is not a codified “both parties” UPAA sentence, although obtaining both
signatures avoids one-sided enforceability questions.

The marriage is the consideration named by the statute and the event the
premarital bargain contemplates. Washington's cases evaluate agreements made
before the wedding and invoked after the marriage.

No notary, witnesses, or recording are universal prenup conditions

RCW 19.36.010 requires the signed writing; it does not add notarization,
acknowledgment, witnesses, attestation, an oath, or recording. A real-property
instrument used to carry out a term can have its own deed or recording rules.

The stricter witnessed-and-acknowledged form in RCW 26.16.120 belongs to the
different spouses' community-property agreement that takes effect on death.
It is not the ordinary premarital validity checklist.

Disclosure becomes decisive when the bargain is substantively unfair

Bernard first asks whether the agreement makes fair and reasonable provision
for the spouse opposing enforcement. If it does, the analysis ends. If it does
not, procedural fairness requires full disclosure of the amount, character,
and value of the property involved.

Washington has no UPAA-style statute supplying a written waiver of further
disclosure or an adequate-knowledge substitute. Knowledge of assets can be
important evidence, but the controlling second prong is the case-law full-
disclosure test.

Counsel and timing belong to the second prong

A substantively fair agreement does not automatically fail because one party
lacked separate counsel. But a substantively unfair agreement must satisfy the
procedural prong: free and voluntary execution on independent advice from
counsel, with full knowledge of each spouse's rights.

Matson directs courts to examine bargaining position, sophistication,
independent advice, understanding of legal consequences, and the timing of
signing relative to the wedding. Washington sets no fixed number of review
days. Matson invalidated an eve-of-wedding agreement where the opposing spouse
had no reasonable opportunity to obtain meaningful independent advice.

Bernard preserves the two-prong execution-time test

The enforcement proponent bears the burden. A substantively fair and reasonable
agreement is enforceable without reaching the procedural prong. A
substantively unfair agreement can still be enforced only if full disclosure,
independent advice, full knowledge, and voluntary execution establish
procedural fairness.

Bernard refused to shift substantive fairness to the time of enforcement,
stating that validity rests on circumstances surrounding execution. Washington
therefore does not use a general changed-circumstances or later-hardship second
look.

A maintenance waiver is part of the fairness analysis

Bernard considered a bargain that prevented one spouse from seeking spousal
maintenance and treated that restriction as part of its conclusion that the
agreement was substantively unfair. A support waiver is not automatically
barred, but it must survive the same two-prong test as the rest of the
agreement.

No Washington premarital statute provides a public-assistance eligibility
override, and Bernard rejected a general enforcement-time unconscionability
test.

Child support and parenting remain court-controlled

RCW 26.09.100 directs the court to order either or both parents to pay child
support under the statewide support schedule after considering the relevant
factors. A premarital bargain cannot replace that statutory judicial order.

For parenting, RCW 26.09.187 requires residential provisions consistent with
statutory limitations and the child's relationships, development, needs, and
best interests. The parties' agreements are factors only when knowing and
voluntary; they do not conclusively dictate a future parenting plan.

A later amendment faces the same fairness review

Washington has no prenup-specific statutory amendment or revocation checklist.
Bernard analyzed a prenup amended after marriage under the same two-prong
framework and stated that postmarital amendment did not alter the analysis. A
marriage-consideration change also must satisfy RCW 19.36.010's signed-writing
rule as applicable.

RCW 26.16.120 separately allows its death-effective community-property
agreement to be amended using the same deed-style formalities. That narrow
route should not be described as the universal change method for an ordinary
prenup.

What trips people up

• RCW 26.16.120 is a different instrument. It applies to spouses or
  domestic partners, community property, and effect upon death.
• Washington does not require both fairness prongs in every case. A
  substantively fair agreement ends the inquiry; procedural fairness is needed
  to save a substantively unfair agreement.
• Counsel has no fixed waiver form. Independent advice and meaningful time
  are fact-specific parts of the procedural test, not a UPAA checkbox.
• The test looks to execution. Bernard rejected a general enforcement-time
  fairness review.

Common questions

Is signing the night before the wedding automatically invalid?

No fixed day count creates automatic invalidity, but Matson shows that eve-of-
wedding timing can defeat procedural fairness when the agreement is unfair and
the opposing party lacks a reasonable opportunity for independent advice.

Who must prove enforceability?

Bernard states that the spouse seeking enforcement bears the burden under the
two-prong test.

Can a later amendment cure an unfair original agreement?

Only if the amendment process itself cures the problem. Bernard held that a
later amendment did not cure the original procedural defects where the allowed
renegotiation was too limited, even though more time and counsel existed later.

Statutes and sources

• RCW 19.36.010(3) — signed-writing statute of frauds for an agreement made
  upon consideration of marriage. Official
  statute (accessed
  2026-07-27).
• In re Marriage of Bernard, 165 Wn.2d 895 (2009) — current two-prong test,
  burden, execution-time fairness, maintenance treatment, and amendment review.
  Washington Supreme Court
  opinion (accessed
  2026-07-27).
• In re Marriage of Matson, 107 Wn.2d 479 (1986) — procedural factors,
  disclosure, independent advice, understanding, and timing. Washington
  Supreme Court opinion
  (accessed 2026-07-27).
• RCW 26.16.120 — separate death-effective community-property agreement
  and its deed-style formalities. Official
  statute (accessed
  2026-07-27).
• RCW 26.09.100 and RCW 26.09.187 — child-support order and parenting-plan
  factors. Official support
  statute and
  parenting statute
  (accessed 2026-07-27).