ERISA automatically makes a surviving spouse the 401(k) beneficiary, overriding any existing beneficiary form unless the spouse signs a notarized waiver after the wedding.
Prenuptial agreements cannot bypass ERISA spousal rights because those rights don't exist until marriage, making a post-wedding consent form the only valid waiver.
Rolling a 401(k) into an IRA removes the spousal consent requirement in most states, letting the owner freely name children as beneficiaries.
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A widower's story travels through estate-planning offices with predictable regularity. A man divorces, updates his 401(k) beneficiary form to name his two children, and moves on. Years later he remarries. When he dies, the plan administrator sends the account to his second wife rather than to the kids. The paperwork he signed was ignored. The reason is federal law, and it is one of the least understood rules in retirement planning.
ERISA, the federal statute that sets the ground rules for private retirement benefits, governs employer-sponsored 401 (k) plans. Under ERISA, a married participant's surviving spouse is the automatic beneficiary of the account unless that spouse signed a written waiver consenting to a different beneficiary. The waiver has to meet the plan's formalities, usually notarization or a plan representative's signature. Without it, the designation form does not control. The spouse does.
Suze Orman has described the underlying principle plainly: "When you have a retirement account, all retirement accounts, and ask you to name a beneficiary, your spouse has different rights than anybody else when it comes to your retirement accounts. Your spouse has the legal authority to take over your retirement account as if it was theirs." That authority is what defeats a pre-marriage designation naming the children.
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The scenario in the headline turns on sequence. The father filled out the beneficiary form after the first divorce, when he was single and free to name anyone. The kids were the logical choice. The moment he remarried, ERISA's spousal protection attached to the account. The old designation remained on file but became unenforceable against the new spouse's statutory claim, because she never signed a waiver giving it up.
A prenuptial agreement generally does not fix this. Courts have repeatedly held that a person cannot waive ERISA spousal rights before becoming a spouse, because the rights do not exist until the marriage does. The spouse must sign the waiver after the wedding, on the plan's form. Anything less leaves the default rule in place, and the default rule sends the money to the current spouse.
Remarriage is not a fringe scenario, as Pew Research reports that about 66% of divorced U.S. adults have remarried, and the Census Bureau tracks divorce rates that, while declining, still produce hundreds of thousands of dissolutions per year. Each of those transitions creates a household where a 401(k) beneficiary form from an earlier chapter may no longer reflect the participant's wishes, and where federal law may override the form regardless.
The account balances at stake are meaningful. Household finances in the aggregate show a country with a thin cushion outside of retirement plans: the personal saving rate was 2.8% in the second quarter of 2026, down from 3.9% in the prior quarter, according to the Bureau of Economic Analysis. For many families, the 401(k) is the largest single asset. Sending it to the wrong beneficiary reshapes the estate.
The fix has to satisfy the plan, not just the participant. The current spouse signs a spousal consent form provided by the 401(k) administrator, waiving her right to the account and acknowledging that the children are named instead. The signature typically has to be notarized. Only then does the beneficiary form naming the kids do what it appears to do.
There is an alternative route, and once a participant separates from service, they can roll the 401(k) into an IRA, and IRAs are not subject to the ERISA spousal consent rule in most states. An IRA owner can name children without a spouse's signature, though community-property states can complicate that outcome. Life insurance and revocable trusts are also common workarounds when a spouse will not sign a waiver, because they let the participant leave assets to children without touching the retirement plan the spouse is entitled to.
The federal rule is the default treatment of every ERISA-covered account in the country. A beneficiary form filled out with the best intentions, kept current for decades, and never disputed by anyone can still be superseded on the day the participant dies if the current spouse never signed a waiver. For remarried workers who want a 401(k) to reach children from an earlier marriage, the signature that matters is the spouse's on the consent form sitting next to the beneficiary form. Most estate messes trace back to a missed form or a stale beneficiary like this one, which is why we put a full cleanup checklist in a free estate guide.
If you've saved over $1,000,000, this guide is for you. The last thing you want in retirement is to run out of money, you want your money to generate lasting income while you enjoy your life.
Now you can learn the strategies wealthy retirees use to fund their retirement with The Definitive Guide to Retirement Income from Fisher Investments. Download the guide today! (sponsor)
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