Updated July 28, 2026. Quick answer: The beneficiary designation controls. Retirement accounts pass outside the will entirely, so an ex-spouse named on a form from 1998 generally inherits regardless of what the will says.
Two documents, and the wrong one usually gets the attention
People spend money on a will and never look at the forms that actually govern their largest accounts. Retirement accounts, and often life insurance, pass by contract to whoever is named — the will does not reach them.
How this goes wrong
- A stale ex-spouse. The most common and most painful case. Divorce does not automatically remove a former spouse from every form, and state rules that purport to help do not always apply.
- A deceased beneficiary with no contingent. Often defaults to the estate — generally the worst outcome.
- A form lost in a custodian merger. If they cannot produce it, the account may default.
Ask every custodian to send you the beneficiary designation currently on file, in writing, and check that primary and contingent are named. This costs an afternoon and prevents the single most expensive category of estate error.
Do it after every life event
Marriage, divorce, a birth, a death, a job change, an account transfer. Any of those can leave a form out of date, and a rollover to a new custodian frequently starts with no beneficiary at all.
Sources
SECURE Act (2019); SECURE 2.0 (2022); final RMD regulations published 19 July 2024; IRC §401(a)(9); IRC §1014 (basis of property acquired from a decedent); IRC §664 (charitable remainder trusts). Cross-checked July 2026 against professional analyses from Kitces, Grant Thornton, Ascensus, Charles Schwab and Kiplinger. Indexed figures and state-specific rules are flagged rather than asserted.
This states what the cited authority says. It is not tax or legal advice, and beneficiary planning turns on family facts and state law that no page can see.