Which Marriages Are Void or Prohibited in Washington?

Most weddings never raise a legal eyebrow. But a small set of marriages are ones Washington refuses to recognize at all, and finding out yours is on that list, sometimes years later, can upend everything from property rights to inheritance. The Law Office of Chad Foster helps Snohomish County clients with divorce and family-law matters.

Washington prohibits three categories of marriage: marriages where either party is under 18, marriages where either party is already married or in a registered domestic partnership with someone else, and marriages between close relatives. These marriages are void, meaning the law treats them as never having existed. A separate, smaller category of marriages is voidable, meaning they stand unless the wronged spouse challenges them. Here is how the two categories work and what to do if your marriage falls into one of them.

The Prohibited Marriages Statute

RCW 26.04.020 is Washington's list of forbidden marriages. It prohibits a marriage when either party has a spouse or registered domestic partner living at the time, unless the registered domestic partner is the other party to the marriage. It also prohibits marriage between people closer in kinship than second cousins, whether the relationship is by whole or half blood, and it separately makes it unlawful to marry your sibling, child, grandchild, aunt, uncle, niece, or nephew. For related guidance, see Actions Must Match Your Words.

The bigamy rule catches more people than you might think, and rarely because anyone intended fraud. A divorce that was never finalized, a foreign divorce that Washington does not recognize, or a forgotten registered domestic partnership can all mean an existing legal relationship was still alive on the second wedding day. For related guidance, see Am I Responsible for My Spouse's Debts From Before We Married.

Underage Marriages Are Now Void Too

Washington's basic marriage statute, RCW 26.04.010, defines marriage as a civil contract between two persons who have each attained age 18. Since a 2024 amendment, the statute goes further: any marriage entered on or after June 6, 2024 where either party is under 18 is void. There is no parental consent workaround and no court approval path anymore. Underage marriages validly entered before that date, or entered in states that allow them, present more complicated recognition questions worth reviewing with a lawyer.

Void Versus Voidable: Why the Difference Matters

A void marriage never legally existed. Neither spouse has to do anything for it to be invalid, no one inherits as a surviving spouse through it, and either party, and in some situations other interested people, can point out its invalidity.

A voidable marriage is different. Under RCW 26.04.130, a marriage is voidable when either party was incapable of consenting for want of sufficient understanding, or when consent was obtained by force or fraud. A voidable marriage remains fully valid unless and until the injured spouse sues to undo it. Only the person laboring under the disability, or on whom the force or fraud was imposed, can bring that challenge. If that spouse instead chooses to stay, the marriage simply continues as if nothing were wrong.

The distinction has real teeth. Suppose a spouse dies. If the marriage was void because of bigamy, the survivor was never a spouse and community property rights never arose. If the marriage was merely voidable for fraud, and no one challenged it during life, the survivor remains a spouse with full inheritance rights.

Out-of-State Marriages: Usually Honored, With Exceptions

Washington follows the general rule that a marriage valid where it was performed is valid here. RCW 26.04.020(3) writes that rule down and carves out the exceptions: an out-of-state marriage is valid in Washington only if it is not bigamous under subsection (1)(a) and not between the close relatives listed in subsection (2), meaning siblings, children, grandchildren, aunts, uncles, nieces, and nephews. Notice what the recognition exception leaves out: the broader in-state ban on marrying anyone nearer of kin than second cousins. First cousins cannot marry inside Washington, but a first-cousin marriage lawfully performed in a state that allows it is recognized here, because first cousins do not appear on the subsection (2) list. That reading follows the statute's text; no Washington appellate court has yet applied subsection (3) to a first-cousin marriage. A bigamous or polygamous marriage, by contrast, is never recognized.

The statute also addresses couples who entered civil unions or domestic partnerships elsewhere. A legal union from another state that provides substantially the same rights as marriage does not bar the couple from marrying each other in Washington.

What to Do If Your Marriage Might Be Void

You do not have to live with the uncertainty. RCW 26.09.040 lets either or both parties petition the superior court for a declaration concerning the validity of the marriage. The court will decide validity as of the date the marriage began, and if it declares the marriage invalid, it still has full power to divide property fairly, order maintenance, and adopt a parenting plan, using the same standards that govern a divorce. Children are fully protected: under RCW 26.09.040(5), any child born or conceived during a marriage of record is legitimate regardless of what the court later says about the marriage itself.

That last point surprises people. A declaration of invalidity is not a legal eraser that leaves the financially weaker party with nothing. Washington courts recognize that people build lives together in reliance on a marriage, and the statute gives judges the tools to unwind those lives equitably. The article on how to get a marriage annulled in Washington walks through that process step by step.

If the problem is instead that your otherwise valid marriage is ending, the path is dissolution rather than a validity challenge, and questions about how property gets divided in a Snohomish County divorce will loom larger than the validity rules discussed here.

Get Clarity Before the Stakes Rise

Validity problems have a way of surfacing at the worst possible moments: during a divorce, after a death, or in an immigration or benefits dispute. If you have any doubt about whether a prior divorce was final, whether an out-of-state marriage or union follows you here, or whether a relative's marriage was valid, it is far cheaper to answer the question now than to litigate it later.

The Law Office of Chad Foster helps clients across Snohomish County untangle marriage validity questions and the property, inheritance, and parenting issues that ride along with them. Call 425.785.8679 for a straight answer about where your marriage stands.