A prenuptial agreement in Washington State must be a written contract, signed by both people before the wedding, that either reads as substantively fair on its face or, if its terms are lopsided, was signed after full financial disclosure, with time to review and ideally independent counsel on each side. Washington has not adopted the Uniform Premarital Agreement Act, so the rules come from case law rather than a single statute, and courts have real discretion to throw out an agreement that fails either the fairness of its terms or the fairness of how it was signed.
The Two-Part Fairness Test from Matson
The controlling framework comes from the 1986 Washington Supreme Court decision In re Marriage of Matson.1Justia. In Re Marriage of Matson A judge first asks whether the agreement is substantively fair, meaning whether its terms produce a fair and reasonable result for the spouse who did not draft it. If the answer is yes, the inquiry stops and the agreement is enforced.
If the terms are grossly disproportionate, the court moves to procedural fairness. That means examining whether both parties made full disclosure of their finances, whether each had the chance to consult independent counsel, and whether there was enough time to review and negotiate. In Matson itself, the agreement was signed only three days after the first meeting to review it, and the court refused to enforce it.1Justia. In Re Marriage of Matson A one-sided agreement can still survive, but only when the process behind it was transparent and unhurried.
Written, Signed, and Properly Executed
Washington courts expect the agreement to be in writing and signed by both parties. No statute specifically mandates notarization, but having both signatures acknowledged by a notary public is standard practice and strengthens enforceability. The notary verifies each signer’s identity and confirms the signing is voluntary under Washington’s Revised Uniform Law on Notarial Acts.2Washington State Legislature. Chapter 42.45 RCW – Revised Uniform Law on Notarial Acts Washington notaries can charge a maximum of $10 per acknowledgment.3Washington Department of Licensing. Washington Laws and Rules
Many attorneys recommend that each spouse’s lawyer sign a certification confirming the client understood the terms and signed voluntarily. It is not a statutory requirement, but it adds evidence that the procedural prong of Matson was satisfied.
Store the signed original somewhere secure, like a fireproof safe or safety deposit box. Recording the agreement with the county auditor is optional and creates a public record of its existence; the base recording fee is $5 for the first page and $1 for each additional page, though surcharges may apply.4Washington State Legislature. RCW 36.18.010 – Fees Collected by County Auditors Because the agreement contains sensitive financial detail, many couples skip recording and keep the original in private storage. Either option is legal, but if the original is lost and only copies remain, the agreement can face extra challenges in court.
Timing, Counsel, and the Absence of Duress
Sign Well Before the Wedding
Timing is where Washington prenups most often fall apart. An agreement handed over days before the ceremony invites a duress finding, because the other party faces the choice between signing unfavorable terms and calling off the wedding. Family law attorneys generally recommend having the final document signed at least 30 to 60 days before the ceremony. That window gives both parties time to read, question, propose changes, and consult counsel without the pressure of an approaching date.
Independent Legal Counsel for Each Spouse
Washington does not technically require each spouse to hire a separate attorney. But the absence of independent counsel is one of the first things a court examines when the agreement is challenged. When only one side had a lawyer, judges often view the process with suspicion and more readily find that the unrepresented spouse did not fully understand what they gave up. Separate attorneys are the single most effective way to show that neither person was pressured. Fees for drafting or reviewing a Washington prenup typically run from about $1,000 to $10,000 per spouse depending on complexity, which is modest next to the cost of litigating over an agreement a court later throws out.
What Counts as Duress
Coercion does not have to look like a direct threat. Washington courts recognize that emotional leverage, financial dependency, and pressure from family can all amount to duress. A “take it or leave it” presentation with no room to negotiate is a warning sign, as are rushed timelines and the lack of any back-and-forth. Judges look at the full picture: whether there was genuine negotiation, whether each person had time to understand their rights, and whether refusing felt impossible.
Full Financial Disclosure
Full financial transparency is the backbone of an enforceable Washington prenup. Under Matson, failing to disclose even one significant asset or debt can give a judge grounds to void the entire contract. Each party should prepare a detailed schedule of what they own and owe, and attach it as an exhibit to the agreement itself.
On the asset side, document real estate holdings with current market values, all bank and brokerage accounts, retirement accounts, stock options, life insurance policies with cash value, vehicles, and any business ownership interests. A business often requires a formal valuation by a certified public accountant to set a baseline both sides accept. Real estate should be supported by a professional appraisal or at minimum a recent comparative market analysis.
Debts need the same granularity. Every student loan, credit card balance, mortgage, car loan, and personal line of credit should be listed with the current balance, lender’s name, and account number. Three years of tax returns along with recent bank and brokerage statements round out the picture. Income documentation should cover current pay stubs, bonus structures, and any expected inheritances or trust distributions. All of this becomes an exhibit to the agreement and creates a permanent snapshot of each person’s finances at signing.
If a spouse later claims they were blindsided by hidden wealth or secret debt, these exhibits are what the court will examine.
What the Agreement Can and Cannot Include
Permissible Terms
A Washington prenup can override the community property default set by RCW 26.16.030, which otherwise treats most wages, investment gains, and debts accumulated during the marriage as owned equally by both spouses.5Washington State Legislature. RCW 26.16.030 – Community Property Defined—Management and Control Couples can designate specific assets as separate property regardless of how they are used during the marriage, treat certain future income as community or separate, allocate responsibility for pre-existing debts so one partner’s creditors cannot pursue the other’s assets, and set valuation rules for a family business.
Spousal maintenance can be limited or waived entirely, but this provision gets the heaviest scrutiny. Courts apply the Matson fairness test with particular intensity to maintenance waivers and weigh the factors in RCW 26.09.090, including each spouse’s financial resources, the time needed to acquire training for appropriate employment, the standard of living during the marriage, its duration, and each party’s age and health.6Washington State Legislature. RCW 26.09.090 – Maintenance Orders for Either Spouse or Either Domestic Partner—Factors A waiver that would leave one spouse destitute or on public assistance after a long marriage may be struck as unconscionable no matter what both parties agreed to beforehand.
Terms That Will Not Be Enforced
No Washington prenup can predetermine child custody or cap child support. Courts keep exclusive authority over anything involving children, and any clause attempting to waive support or lock in a parenting plan is unenforceable.7Washington State Legislature. RCW 26.09.002 – Policy Child support is calculated under a mandatory statewide schedule based on both parents’ incomes and the child’s needs.8Washington State Legislature. RCW 26.19.035 – Standards for Application of the Child Support Schedule The right to support belongs to the child, so neither parent can bargain it away.
Washington is also a no-fault divorce state, so clauses that impose penalties for infidelity, weight gain, or other personal behavior sit uneasily with a system designed to exclude fault. No Washington appellate court has issued a definitive ruling on infidelity penalties, but the no-fault framework makes enforcement unlikely, and these clauses should not be relied on.
Living by the Agreement After It Is Signed
The requirements do not stop at the signing table. Washington law is unusually flexible about rescission: an agreement to undo a prenup can be oral, written, or even implied by the parties’ conduct. If both spouses ignore the prenup’s terms throughout the marriage, a court may find the agreement was effectively abandoned. If a prenup designates certain income as separate property but both spouses treat it as community money for years, the spouse later trying to enforce the original terms bears the burden of showing the agreement was observed in good faith.
Couples who want flexibility sometimes include a sunset clause that causes the agreement to expire after a set number of years, often tied to a milestone anniversary. Any formal modification should follow the same safeguards as the original: written, signed voluntarily, backed by current financial disclosure, and ideally reviewed by separate attorneys. Oral modifications are theoretically valid but extremely difficult to prove and are best avoided.
If You Missed the Prenup Window
Couples who did not sign before the wedding can enter into a postnuptial agreement afterward. Washington courts recognize them but scrutinize them more closely than prenups, because spouses already owe each other fiduciary duties once married. The same requirements apply: full disclosure, voluntary signing, and terms that are not grossly one-sided. Each spouse should have independent counsel, and the same documentation standards described above should be followed.