The 401(k) Beneficiary Mistake That Could Send $400,000 to the Wrong Person

A $400,000 401(k) does not follow the will. It follows the beneficiary form. For a surprising number of account holders, those two documents point to different people, and the account holder has no idea.

Why ERISA Overrides Everything Else

401(k) beneficiary designations are governed by ERISA and override any instructions in a will, trust, or divorce decree. The U.S. Supreme Court confirmed it in Egelhoff v. Egelhoff (2001), holding that ERISA preempts state laws that would automatically revoke a former spouse’s beneficiary designation upon divorce.

The practical consequence: if a participant names their spouse as beneficiary during a marriage and later divorces but never updates the designation, the ex-spouse receives the full 401(k) balance upon the participant’s death, regardless of what the divorce settlement said. A new will naming the children as heirs has no effect on the 401(k) distribution. A divorce decree stating that the ex-spouse waives rights to retirement assets is enforceable only if the waiver was executed through the proper legal instrument.

The QDRO Gap That Divorce Attorneys Miss

Divorce decrees that purport to transfer 401(k) assets to the non-participant spouse require a Qualified Domestic Relations Order (QDRO), a separate legal document that must be approved by the plan administrator. A divorce settlement that simply states one spouse receives a portion of the other’s 401(k) is legally insufficient on its own. Without a QDRO, the transfer cannot be executed.

This matters in two directions. First, a participant who intends to keep their full 401(k) balance but whose divorce attorney failed to secure a QDRO may face a legal dispute years later. Second, a participant who updated their beneficiary form after divorce but whose ex-spouse was awarded a share of the account through the divorce settlement, without a QDRO, leaves that transfer in legal limbo. A divorce attorney who fails to obtain a QDRO has made a costly error.

The Tax Consequence No One Anticipates

The misdirected inheritance problem compounds when the wrong beneficiary is also the wrong type of beneficiary for tax purposes. A surviving spouse who inherits a 401(k) can roll it into their own IRA, defer distributions, and manage withdrawals strategically. Non-spouse beneficiaries, including adult children, must empty the inherited account within 10 years of the original owner’s death under the SECURE Act rules.

On a $400,000 traditional 401(k), that 10-year distribution window could push an adult child earning $120,000 per year into a significantly higher bracket in the years they take distributions. Inherited traditional 401(k) distributions are taxed as ordinary income at the beneficiary’s rate. If the wrong person inherits, the tax outcome changes entirely.

The Contingent Beneficiary Problem

Naming only a primary beneficiary without a contingent beneficiary means the 401(k) passes through probate if the primary beneficiary predeceases the participant. Probate can delay distribution for months or longer, expose the account to creditor claims, and generate legal fees that reduce what heirs actually receive. A beneficiary designation transfers assets outside of probate. A missing contingent beneficiary precludes that outcome in a foreseeable scenario.

The fix is straightforward. Naming a contingent beneficiary takes the same amount of time as naming the primary. Most plan portals accept multiple contingent beneficiaries with percentage allocations.

Steps That Affect Who Receives the Account

1. Log in to the plan portal and locate the beneficiary section. This takes under five minutes and can determine who receives hundreds of thousands of dollars. Verify that both the primary and contingent designations reflect current intentions. If a divorce occurred at any point and the form was not updated afterward, treat this as urgent.
2. If a divorce involved retirement assets, confirm whether a QDRO was executed and approved by the plan administrator. A divorce decree alone is not sufficient. The QDRO must have been submitted to and accepted by the plan. If it was not, consult a family‑law attorney who specializes in the division of retirement assets.
3. Review beneficiary designations after every major life event. Marriage, divorce, the death of a named beneficiary, and the birth of a child or grandchild all create potential mismatches between the current form and current intent. Plan administrators follow the form on file, not the participant’s intended form.