A prenup generally overrides a will when the two documents address the same property, so the short answer to whether a will overrides a prenup is usually no. A prenuptial agreement is a contract signed by both spouses, and one spouse cannot rewrite that contract alone by drafting a later will. The picture gets more complicated once you look at retirement accounts, assets with named beneficiaries, and state elective-share laws, each of which can override the prenup, the will, or both.
Why the Prenup Usually Wins
A prenuptial agreement is a contract two people sign before marriage. It has to be in writing, signed voluntarily, and supported by honest financial disclosure from both sides to hold up in court.1International Academy of Family Lawyers. Prenuptial Agreements in the United States Neither party can change the terms alone.
A will is the opposite kind of document. You write it, you can change it whenever you want, and nobody else signs off. It only governs assets that pass through probate.2American Bar Association. Introduction to Wills
When the two conflict, courts treat the prenup as a bargained-for exchange that both spouses relied on. One person’s later instructions cannot undo a two-person contract.
When a Prenup Controls Over a Will
Courts are most likely to enforce a prenup over a conflicting will when the prenup explicitly addresses what happens to property at death. The clearest example is an inheritance waiver, where each spouse gives up any claim to the other’s estate. If your prenup contains that kind of waiver and your will later tries to leave your spouse more, or your spouse tries to claim more, the waiver controls.
The same is true when the prenup routes specific assets to specific people, such as children from a prior marriage. A later will that tries to redirect those assets to the surviving spouse runs into the prior contract and loses.
When a Will Can Prevail
A will can effectively govern in a few specific situations.
The most common is when the prenup simply does not address death. Many prenups are drafted with divorce in mind and say nothing about estate distribution. When the prenup is silent on post-death rights, the will controls those issues.
A will also prevails when the prenup itself is invalid. If a court throws out the agreement for duress, missing financial disclosure, or unconscionable terms, the will and state default rules fill the gap.
Some prenups include sunset clauses that terminate the agreement after a set number of years, often 10 or 15. Once the prenup has expired, there is no competing contract and the will governs.
Finally, spouses can mutually agree to modify or revoke the prenup during the marriage and then write new wills reflecting the updated plan. That works because both parties consented. One spouse writing a new will alone does not undo a valid prenup.
Retirement Accounts Follow Federal Rules, Not Your Prenup
This is where most assumptions about prenups break down. Federal law, not state contract law, governs benefits like 401(k) plans and traditional pensions. Under ERISA, a participant’s spouse has an automatic right to survivor benefits, and waiving that right requires written consent from the spouse, acknowledged before a plan representative or notary.3Office of the Law Revision Counsel. 29 U.S. Code 1055 – Requirement of Joint and Survivor Annuity and Preretirement Survivor Annuity
ERISA only recognizes waivers from a “spouse.” When you sign a prenup, you are not yet married, so you are not yet a spouse for ERISA purposes. Courts have consistently held that a prenuptial waiver does not satisfy ERISA’s spousal consent requirements, even when the prenup specifically names the retirement account. The waiver has to specifically acknowledge the effect of giving up the benefit and be witnessed by a plan representative or notary.
The fix is to sign a separate beneficiary waiver directly with the plan administrator after the wedding. If your prenup says your spouse gets nothing from your 401(k) but you never complete the plan-specific waiver, your spouse still has a legal right to those benefits regardless of what the prenup or your will says.
Beneficiary Designations Bypass Both Documents
Retirement accounts are part of a broader category of assets that pass outside both your will and your prenup. Life insurance policies, IRAs, payable-on-death bank accounts, and transfer-on-death brokerage accounts all go directly to whoever is listed as the beneficiary on the account paperwork. Your will cannot redirect them, and your prenup cannot automatically change them either.
This creates a common failure. Someone signs a prenup keeping certain assets separate, writes a will consistent with that agreement, and never updates the beneficiary forms. When they die, the old beneficiary designation controls, and the assets go somewhere neither document intended.
Elective Share Laws Can Override Both
Most states have elective share statutes designed to prevent one spouse from completely disinheriting the other. These laws give the surviving spouse the right to claim a minimum percentage of the deceased spouse’s probate estate regardless of what the will says. The traditional share is one-third, though some states use a sliding scale based on the length of the marriage, ranging from zero for marriages under one year to 50 percent for marriages of 15 years or more.4Legal Information Institute. Elective Share
A prenup can waive the elective share, and most states will enforce that waiver as long as the prenup itself is valid. The waiver usually has to be explicit. A general statement that each spouse keeps their own property may not be enough; courts look for language showing the spouse understood they were giving up a specific statutory right. Some states impose additional formalities, such as requiring the waiver to be acknowledged the same way a real estate deed would be.
If the prenup does not mention the elective share at all, the surviving spouse can usually still claim it, and that claim can override both the prenup and the will.
What Can Invalidate a Prenup
When a prenup falls apart, the will and state default rules take over. Courts look at several factors when deciding whether to throw out a prenup:
- Duress or coercion. Presenting a prenup days before the wedding with a take-it-or-leave-it ultimatum is the classic fact pattern. The closer to the wedding the agreement was signed, the more skeptical courts become.
- Incomplete financial disclosure. Both parties must provide an honest picture of their assets, debts, and income. Hiding significant assets or misrepresenting a financial situation can void the entire agreement.
- Unconscionability. Terms so lopsided they would leave one spouse destitute or dependent on public assistance are unlikely to survive a challenge. Courts are especially cautious when the unfairness was not apparent at signing but became extreme over a long marriage.
- Lack of independent legal counsel. Most states do not require both parties to have their own attorney, but courts view prenups with much greater skepticism when one side had no legal representation.
Any one of these defects can sink the whole prenup or specific provisions within it. In the estate context, that means the surviving spouse regains whatever rights state law would have provided, including elective share claims the prenup tried to waive.
Keeping Your Prenup and Will Consistent
Most conflicts between these documents come from neglect rather than deliberate contradiction. People sign a prenup, get married, draft a will years later with a different attorney, and nobody checks whether the two documents match. A few practical steps prevent that:
- Draft both documents with the same goal in mind. Your will should carry out the promises made in your prenup. Estate planners recommend that any prenup provisions intended to apply at death be incorporated into the will or a revocable trust.5ACTEC Foundation. Mistakes Made in Premarital Agreements by Estate Planning and Family Law Lawyers
- Update beneficiary designations after the wedding. Review every retirement account, life insurance policy, and payable-on-death account so the named beneficiaries match what your prenup and will intend.
- Complete ERISA waivers separately. If your prenup addresses retirement benefits, sign the required spousal consent forms with each plan administrator after you are married.3Office of the Law Revision Counsel. 29 U.S. Code 1055 – Requirement of Joint and Survivor Annuity and Preretirement Survivor Annuity
- Consider a revocable trust. Assets in a trust do not pass through probate, so the will does not govern them. A trust can be structured to carry out the prenup’s terms.
- Review everything after major life changes. A new child, a significant change in wealth, a move to a different state, or the expiration of a sunset clause can all open gaps between what your documents say and what you actually want.
Families that end up in court over prenup-versus-will disputes almost always had documents that were drafted in isolation, by different lawyers, at different times, with nobody checking the full picture. Getting it right at the front end is far cheaper than litigating it later.