For a will to be valid in the United States, the person making it must be at least 18 and mentally competent, the document must be in writing, the maker must sign it, and at least two disinterested adults must witness that signature. Those are the requirements for a valid will across almost every state. Miss any one of them and a probate court has grounds to throw the whole document out.
Who Can Make a Will
The person making the will, called the testator, has to be a legal adult. Nearly every state draws that line at 18.1Legal Information Institute. Testamentary Capacity A few states carve out exceptions for minors who are married, emancipated, or in the military, but those situations are uncommon enough that 18 is the practical cutoff.
Age alone is not enough. The testator also needs what the law calls testamentary capacity, which means being of sound mind at the moment of signing. This is a lower bar than it sounds. Someone with early-stage dementia or periodic confusion can still have capacity if, when they sign, they understand four things: that they are making a will, what they own in general terms, who their close family members are, and how those pieces fit together into a plan for their property.1Legal Information Institute. Testamentary Capacity Capacity is judged at the signing ceremony itself, not weeks before or after. This is why most will contests start here: a disappointed heir argues the testator was not clear-headed on the day the pen hit the page.
The will also has to reflect the testator’s own choices. If someone in a position of trust pressured or manipulated the testator into favorable provisions, a court can invalidate those provisions under the doctrine of undue influence.
The Writing Requirement
A will has to exist as a written document. It can be typed, printed, or handwritten, but it must be readable.2Legal Information Institute. Wills Writing Requirement Oral wills, called nuncupative wills, are not valid in most states. The handful of states that still recognize them restrict their use to narrow circumstances like active military service during armed conflict or mariners at sea.3Legal Information Institute. Nuncupative Will
Two variations on the writing requirement are worth knowing about:
A holographic will is one written entirely in the testator’s own handwriting and signed by them. Because the handwriting itself works as evidence of authenticity, a holographic will does not need witnesses in states that recognize them.4Legal Information Institute. Holographic Will About half the states accept them. Rules differ: some require the whole document to be handwritten, others only the key provisions. Pre-printed fill-in-the-blank forms often fail because the printed text is treated as a material part of the document. A holographic will beats dying with no will at all, but it invites challenges over authenticity and interpretation.
An electronic will is one created and signed digitally. As of 2024, roughly seven states and the District of Columbia had enacted legislation allowing them. These statutes generally require readable text, two witnesses who add their own electronic signatures, and tamper-evident storage. Some states insist on in-person witnessing; others allow witnesses to join by video. Electronic wills remain the exception, and anyone considering one should confirm their state accepts the format before relying on it.
Signing the Will
The testator has to sign. If a physical disability prevents that, another person can sign for them, but only in the testator’s presence and at the testator’s direction.5Legal Information Institute. Wills Signature Requirement The signature does not have to be a full legal name. Courts have accepted initials, nicknames, and even an “X,” as long as the testator meant the mark to be their signature and witnesses observed the act.
Some states require the signature at the end of the document; others allow it anywhere.5Legal Information Institute. Wills Signature Requirement Signing at the end is the safer practice everywhere. It confirms the testator approved everything above the signature and blocks any argument that pages were added later.
Choosing Your Witnesses
Almost every state requires at least two witnesses to watch the testator sign and then sign the document themselves.5Legal Information Institute. Wills Signature Requirement Witnesses do two jobs: they confirm the person signing is actually the testator, and they can later attest the testator seemed competent and unpressured. They do not need to read the will or know its contents.
Witnesses have to be adults, mentally competent, and disinterested, meaning they do not stand to inherit anything under the will. The reason is obvious: a beneficiary has a motive to pressure or deceive the testator.
If a beneficiary does end up signing as a witness, the usual outcome is not that the will fails. Most states have a “purge” statute: the will stays valid, but the witness-beneficiary forfeits their gift, either entirely or down to whatever they would have inherited if there had been no will. A minority of states look at the testator’s intent and circumstances before deciding. The simplest fix is to pick witnesses who are not named anywhere in the document.
Add a Self-Proving Affidavit
A self-proving affidavit is not required for a will to be valid, but leaving it off creates avoidable trouble in probate. The affidavit is a sworn statement, signed by the testator and witnesses before a notary, confirming that all the signing formalities were followed.6Legal Information Institute. Self-Proving Will Almost every state allows it.
Here is why it matters. Without the affidavit, the probate court may need the witnesses to appear in person and testify that they watched the testator sign. By the time probate opens, witnesses may have moved, died, or become hard to track down. A self-proving affidavit lets the court accept the will without any witness testimony at all.6Legal Information Institute. Self-Proving Will Notary fees run from about $2 to $25 depending on the state. There is no sensible reason to skip it.
What a Valid Will Still Cannot Do
A will that meets every formal requirement can still be partially overridden by law. Two protections catch people off guard.
A Surviving Spouse’s Elective Share
Most states give a surviving spouse an “elective share,” a minimum portion of the deceased spouse’s estate guaranteed by statute regardless of what the will says. The traditional fraction is one-third.7Legal Information Institute. Elective Share If the will leaves the spouse less, the spouse can petition the court for the statutory share instead. Community property states work differently: the surviving spouse already owns half the marital property automatically, so the will only controls the deceased spouse’s separate property and their half of the community assets. You cannot disinherit a spouse through a will alone. It takes a valid waiver, usually a prenuptial or postnuptial agreement.
Children Left Out by Accident
Most states have “pretermitted heir” statutes that protect children unintentionally omitted from a will. If a child is born or adopted after the will was executed and the will does not account for them, that child can claim the share they would have received if there had been no will.8Legal Information Institute. Pretermitted Heir Some states extend the rule to any omitted child, not just those born later. The protection does not apply when the will clearly shows the omission was intentional. If you want to disinherit a child, say so in the document rather than leaving the name out.
Keeping the Will Valid: Changes and Revocation
A valid will stays in force until the testator revokes or replaces it. There are three recognized ways to do that.
- Execute a new will. This is the most reliable method. The new will should include language revoking all prior wills and codicils, and it has to meet the same formalities to work.
- Physically destroy the original. Burning, tearing, or shredding the document with the intent to revoke works, but only if the testator does it personally or directs someone to do it in their presence. If copies exist and the original disappears, some courts presume the testator destroyed it; others may accept a copy as valid.9Legal Information Institute. Revocation of Will by Act
- Add a codicil. A codicil amends specific parts of an existing will without replacing it. It has to meet the same requirements as the original: in writing, signed, and witnessed. Crossing out lines or writing in the margins of the original does not count.
Some life events change a will by operation of law. In most states, divorce automatically revokes provisions benefiting the former spouse. Marriage or the birth of a child may trigger the pretermitted heir and spousal protections described above.
What a Will Does Not Need
A few myths are worth clearing up. A will does not have to be drafted by a lawyer, though professional drafting reduces the risk of ambiguity. It does not have to name an executor; if it does not, the probate court appoints one. It does not have to be filed with any court or government office during the testator’s lifetime. And it does not have to be notarized to be valid. Notarization comes in only through the self-proving affidavit, which is optional but worth the small fee for everyone.