Postnuptial Agreements in Washington: What They Can Cover and When Courts Enforce Them

Married couples in Washington sometimes assume the chance to set financial rules ended at the wedding. A postnuptial agreement is a contract spouses sign after they are already married, covering property, debt, and sometimes spousal maintenance if they later separate, and how those rules relate to death. It is a planning document. It is not proof the marriage is over.

This article explains how a Washington postnup differs from a prenup and from a statutory community property agreement, what it can and cannot cover, and what courts weigh when one spouse asks to enforce it. It is general education for Pierce County families, not legal advice about your draft.

A Postnup Is Not a Prenup Signed Late

A prenuptial agreement is signed before the marriage. Our guide to whether you need a prenup in Washington covers that timing, including why a draft that appears days before the ceremony is a common fact pattern in a later challenge.

A postnup comes after the wedding, when the community may already own the house, the paychecks, and the retirement contributions. In re Marriage of Matson, 107 Wn.2d 479 (1986), holds that people negotiating a prenuptial agreement do not deal at arm's length and must exercise a high degree of good faith, candor, and sincerity. A postnup is negotiated inside an existing marriage, so those concerns apply with at least as much force. There is no wedding-day deadline, but there can still be pressure — a threat to leave, a promise to reconcile, or one spouse controlling the books. Registered domestic partners are in a comparable position under the community-property statutes.

Community Property Is the Backdrop

Under RCW 26.16.030, property acquired after marriage is generally community property, even if one name is on the account. Separate property, under RCW 26.16.010 and RCW 26.16.020, is generally what a spouse owned before marriage or later received by gift or inheritance, plus profits that stay identifiable. If the marriage ends, RCW 26.09.080 requires a just and equitable division of community and separate property and debts. That is not an automatic 50/50 split. How characterization, tracing, the house, and debts work is in our guide to property division. An enforced postnup can supply the rule for what it validly covers.

RCW 26.16.140 treats earnings after spouses are living separate as separate property. Living separate is a legal status. Spouses who still share a household and a joint budget in Puyallup or on South Hill are usually still a community. An agreement signed after an actual separation may instead be a separation contract.

A Community Property Agreement Is a Different Instrument

People use 'postnup' for any contract signed after the wedding. RCW 26.16.120 is narrower. It lets spouses or registered domestic partners agree on the status or disposition of community property they own or later acquire, to take effect at the death of either. The instrument must be in writing and witnessed, acknowledged, and certified in the same manner as a deed to real estate. It may be amended the same way. It shall not derogate from the rights of creditors, and it does not curtail the superior court's power to set it aside for fraud or another recognized ground of equity.

Lawyers call that a statutory community property agreement. Estate planners use it so property passes to the surviving spouse, sometimes after the spouses agree on community character. It is aimed at death. It does not, by itself, decide who keeps a business or a house in a divorce.

RCW 26.09.070 is the separation contract spouses use when they are separating or a dissolution, legal separation, or invalidity case is filed. It may cover maintenance and property. If it was fair when signed, it binds the court except for parenting-plan terms, and any child-support figure is reviewed under RCW 26.19.020. A couple still sharing an economic life is usually signing a marital agreement under the case law below. A couple already dividing a life in a Pierce County case is often signing a separation contract.

Why Couples Sign One After the Wedding

• A new business, a practice buy-in, or equity compensation, including how to treat the other spouse's labor
• An expected inheritance or gift the couple wants to keep identifiable
• A reconciliation after separation, with the financial terms in writing
• New business debt, student loans, or a personal guarantee the spouses want to allocate between themselves
• A career change, including leaving paid work or a military retirement connected to Joint Base Lewis-McChord
• Children from a prior relationship, and property rules that can line up with an estate plan

Those facts are reasons to talk before money is mixed past the point of tracing. They do not guarantee that a court will enforce whatever gets signed.

What a Washington Postnup Can Cover

A negotiated agreement commonly sets the character of assets and debts the spouses already hold and of property they expect to acquire: a business or equity award, a premarital house, an inheritance kept identifiable, and a debt allocated between the spouses. It can also address spousal maintenance, including a defined approach, a waiver, or a reservation. A waiver that leaves one spouse with no realistic provision while the other's separate estate grows on community labor is the pattern In re Marriage of Bernard, 165 Wn.2d 895 (2009), and In re Marriage of Foran, 67 Wn. App. 242 (1992), treated as substantively unfair.

The agreement does not rewrite a creditor's contract. RCW 26.16.120 says a community property agreement shall not derogate from the rights of creditors, and a lender can still collect from anyone who signed the note. A sentence about a 401(k) or pension also does not move the money. Private ERISA plans pay on a qualified domestic relations order the administrator accepts; Washington public plans pay on a Department of Retirement Systems order; beneficiary forms are separate. That paperwork is in Dividing Retirement Accounts in a Washington Divorce.

What It Cannot Cover

Parents cannot contract the court out of decisions about their children. Under RCW 26.09.070, a separation contract that was fair at execution binds the court except for parenting-plan terms. Residential time and major decisions are made under the child's best interests when a case is filed. A clause that awards 'custody,' or that locks a child into one school district, does not control the later parenting plan.

Child support belongs to the child. A number in a separation contract is reviewed against the Washington State Child Support Schedule under RCW 26.19.020. A waiver or a token amount does not bind the court, and calling the document a postnup does not create an opt-out. The agreement also cannot take away the court's power to refuse an unfair bargain or to set one aside for fraud, and it does not replace a will, a beneficiary form, or the orders that end a marriage. That path is in our step-by-step divorce guide.

When Washington Courts Enforce the Agreement

Washington has not adopted the Uniform Premarital Agreement Act. The Supreme Court uses the two-prong analysis in Matson, restated in Bernard, and places the burden of proof on the spouse seeking enforcement. Bernard takes that burden from Friedlander v. Friedlander, 80 Wn.2d 293 (1972). Spouses asking a court to enforce a postnuptial agreement should expect the same framework. Being married does not lower it.

Substantive fairness comes first: does the agreement make a fair and reasonable provision for the spouse who is not seeking to enforce it? If it does, the analysis ends and the agreement is enforceable. Bernard measured that question at signing and refused to move it to the enforcement date. Judging fairness by how the marriage turned out, the court said, would change the test from fairness to fortuity. An agreement that limits one spouse's ability to accumulate property and cuts off claims to the other's separate estate can fail this prong. Bernard quoted In re Marriage of DewBerry, 115 Wn. App. 351 (2003), for a fair contrast: two working spouses may agree that each keeps the fruits of their own labor.

Procedural fairness is the second prong, and the court reaches it only when the terms are substantively unfair. It asks whether the spouses fully disclosed the amount, character, and value of the property, and whether they signed freely and voluntarily, on independent advice, with full knowledge of their rights. A fair process can bind them to an unequal division. If the terms and the process both fail, the agreement is unenforceable — the result Bernard affirmed, even after a later amendment.

The second prong is a facts inquiry. In Bernard, a draft delivered days before a large wedding, and counsel with time only to flag the high points, did not become fair because the spouses signed a limited amendment later. Foran held that telling someone to hire a lawyer, without a real understanding of the economics, was not enough. Matson, discussing Whitney v. Seattle-First National Bank, 90 Wn.2d 105 (1978), treats independent advice as a circumstance of the case: missing counsel does not automatically void a fair agreement, and having counsel does not save a signing the client did not understand. Pierce County families present the document in Pierce County Superior Court in Tacoma. The court applies this test then.

How a Sound Agreement Is Put Together

1. Name the problem — a business, an inheritance, a reconciliation, a debt, or a career change — and say what the agreement is not deciding.
2. Exchange complete records: accounts, retirement, business interests, real estate, debts, and known expected gifts or inheritances. Disclosure is of amount, character, and value.
3. Each spouse should have a separate lawyer and time to read a real draft. Independent counsel is the practical protection; a rushed review is not.
4. If the document is a statutory community property agreement under RCW 26.16.120, use the deed formalities. If it is meant to govern a future dissolution, say so, and leave parenting and child support out of the property clauses.
5. Sign without a manufactured emergency. Voluntariness is part of the legal test.
6. Match the rest of the paperwork: titles you actually intend to change, beneficiary designations, and the estate plan.
7. Amend later only in a new writing with the same disclosure and advice. One spouse cannot revise it alone.

A postnuptial agreement lets spouses who are already in Washington's community property system write a clearer rule for a business, an inheritance, a debt, or a reconciliation. It holds up when the terms were a fair provision at signing, or when full disclosure and a voluntary, informed signing support an unequal bargain. It cannot set a parenting plan, waive a child's support, or survive a pressured and uninformed signing. If you are considering one, or you were handed a draft, our family law practice can help you decide whether an agreement fits. The office is at 1103 Shaw Road in Puyallup, and we work with families throughout Puyallup and Pierce County.