How Do Prenups Work With Retirement Accounts?

Retirement accounts are often a couple's largest asset, and many people assume a prenuptial agreement can lock them down completely. It can do a lot, but there is one federal rule that trips up even carefully written agreements.

For related help, see divorce help, prenuptial-agreement guide, and property-division guide.

Separate Versus Community, and Where Retirement Fits

Washington is a community property state, so the starting point is how the law characterizes what each spouse owns. Property owned before marriage, or received during marriage by gift or inheritance, is separate property that a spouse can manage and dispose of on their own. See RCW 26.16.010. Property acquired during the marriage, by contrast, is generally community property owned equally by both spouses. See RCW 26.16.030. A retirement account often straddles this line. Contributions made and growth earned before the wedding tend to be separate, while contributions and growth during the marriage tend to be community. Over a long marriage, an account that started as one spouse's separate property can become a mix of separate and community interests that is difficult to untangle at divorce or death.

A prenuptial agreement can cut through that complexity. Two people can agree in advance that a retirement account, including future contributions and the growth on it during the marriage, will be treated entirely as one spouse's separate property. Because RCW 26.16.010 and RCW 26.16.030 turn on whether property is separate or community, an agreement that fixes the character of the account changes the analysis a court would otherwise perform. This is a common and useful reason to sign a prenup, especially where one spouse enters the marriage with a substantial 401(k), pension, or IRA and wants to keep it clearly on their own side of the ledger.

The ERISA Catch That Surprises People

Here is the part that surprises many couples. Characterizing an account as separate property under state law is not always the same as controlling who receives it when the account holder dies. Many employer-sponsored retirement plans, including most 401(k) plans and traditional pensions, are governed by a federal law known as ERISA. Federal law generally requires that a married participant's surviving spouse be the beneficiary of certain plan benefits unless the spouse consents in writing to waive that right. And here is the wrinkle: that consent generally has to come from a spouse. A fiance who signs a prenup before the wedding is not yet a spouse, so a court may find that a prenuptial waiver does not satisfy the federal requirement for a valid spousal waiver of ERISA plan survivor benefits.

The practical consequence is that a prenup alone may not accomplish what the couple intended for these plans. Even if the agreement clearly states that the participant's spouse waives all rights to a 401(k), the plan may still owe survivor benefits to the surviving spouse unless a proper waiver was signed after the marriage. The fix is usually straightforward once you know to do it: after the wedding, the spouse signs a separate, plan-compliant beneficiary waiver, often on the plan administrator's own form and frequently with notarization or plan witnessing. That post-marriage spousal waiver, not the prenup, is what actually releases the ERISA survivor rights.

This federal caveat does not apply the same way to every account. IRAs are not ERISA plans and follow different rules, so a prenup and coordinated beneficiary designations carry more weight there. The point is that the type of account matters, and a one-size-fits-all clause in a prenup can create a false sense of security for the accounts where federal law has the final say.

Making the Agreement Enforceable in the First Place

Whatever the account type, the prenup only works if it holds up. Washington has no statute setting the rules for prenuptial agreements, so enforceability comes from case law, principally In re Marriage of Matson, 107 Wn.2d 479 (1986). Under Matson, a court first asks whether the agreement made a fair and reasonable provision for the spouse not seeking to enforce it. If not, the court examines the process: whether both parties disclosed their assets fully, whether each understood what they were giving up, whether each had a real opportunity for independent legal advice, and whether the signing was voluntary rather than rushed or pressured. An agreement that assigns a large retirement account entirely to one spouse invites exactly this kind of scrutiny, so full disclosure and unhurried, independently advised signing are not just good practice, they are what keeps the clause standing.

Getting Both Layers Right

Retirement accounts call for a two-layer approach. The prenup handles the state-law characterization, keeping the account clearly separate under RCW 26.16.010 and RCW 26.16.030 and setting expectations for divorce. The post-marriage spousal waiver, where an ERISA plan is involved, handles the federal survivor-benefit rule that the prenup cannot reach on its own. Skipping the second layer is one of the most common ways a well-intentioned agreement fails to do what the couple wanted.

If you live in Snohomish County and are bringing a pension, 401(k), or other retirement savings into a marriage, this is an area where the details genuinely decide the outcome. The Law Office of Chad Foster can help you structure a prenuptial agreement and the follow-up waivers so your retirement assets end up where you intend. Reach out to talk through what makes sense for your situation.