Any person who is at least 18 years old and of sound mind can make a will in the United States, and the question of who can make a will comes down to those two basics plus genuine intent and proper signing. A few narrow exceptions let certain minors sign a will before 18, and citizenship is not a requirement at all. The rest of what makes a will stick is about how you sign it and whether anyone can later show you were pressured, tricked, or not thinking clearly at the moment you put pen to paper.
The Age Requirement
Every state sets 18 as the minimum age to make a will, with Louisiana as the notable outlier at 16. The rule tracks the Uniform Probate Code, which allows “any person 18 or more years of age who is of sound mind” to make a will. A will signed by someone under the required age is generally void from the start and will not be accepted in probate.
When Minors Can Make a Will
Several states let people under 18 make a valid will when they have already taken on adult responsibilities:
- A minor who has been legally emancipated, typically through a court order releasing them from parental control, can make a will in states that recognize this exception.
- Roughly fourteen states, including Texas, California, Virginia, and Kansas, allow a minor who is legally married to execute a will before turning 18.
- Active-duty military members have access to military testamentary instruments under federal law. These are prepared with help from a military legal assistance attorney and executed with specific formalities including notarization and at least two witnesses. Some states also recognize separate “soldier’s will” provisions that relax the usual formalities for service members.1Office of the Law Revision Counsel. 10 USC 1044d – Military Testamentary Instruments
Outside these categories, a person under 18 cannot make a valid will no matter how mature or financially independent they are.
What “Sound Mind” Actually Means
Being old enough is not enough. You also have to be mentally capable at the moment you sign. Courts apply a four-part test that has been part of probate law for more than a century. To have the capacity to make a will, you must be able to understand all four of these things when you sign:
- That the document you are signing is a will meant to distribute your property after your death.
- What you own, in general terms. A rough sense of your home, accounts, investments, and belongings is enough; you do not need an exact inventory.
- Who your close family members are — the people who would normally expect to inherit from you, such as a spouse, children, or other close relatives — even if you decide not to leave them anything.
- How those pieces fit together into a plan: which assets go to which people and why.
This bar sits deliberately lower than the mental capacity the law demands for other legal acts, like negotiating a business contract. Leaving your house to your children is a simpler decision than bargaining over the terms of a complex agreement, and courts treat it that way. The question is whether you understood the basic nature of what you were doing, not whether you could have managed a complicated financial transaction.
Capacity Is Measured at the Moment of Signing
Capacity is judged at the exact moment you sign, not the day before and not the week after. Someone with a progressive condition like dementia can still make a valid will during a period of mental clarity. These windows are sometimes called lucid intervals, and courts have long recognized them as legally sufficient for signing a will.
Evidence of confusion or memory problems at other times does not automatically invalidate a will if the person met the four-part test during the signing itself. Witnesses matter here because they observe your demeanor and can later testify about whether you appeared alert, understood what was happening, and acted voluntarily. That is one of the reasons the law requires witnesses in the first place.
Insane Delusions
A will can still be challenged even when the person passed the general capacity test, if they were acting under what the law calls an insane delusion. This is not an unusual opinion or an eccentric preference. It is a persistent false belief, held against all evidence, that directly affected how the will distributes property.
If a parent falsely believes without any factual basis that one of their children tried to poison them, and disinherits that child on that basis, a court could find that an insane delusion tainted that part of the will. The critical question is whether the delusion materially changed the outcome. A false belief that did not affect who gets what is unlikely to invalidate the document.
You Have To Actually Intend It As Your Will
Age and mental capacity are not the whole story. You also have to intend the document to serve as your will. A paper signed as a joke, as a sample, or under the mistaken belief that it was something else — like a power of attorney — lacks testamentary intent and is not valid.
Intent breaks down into two practical requirements. First, your decision has to be freely formed. If someone uses threats, emotional manipulation, or lies to pressure you into signing, the will can be thrown out. Second, you have to know what the document actually says. A person who signs a stack of papers without realizing a will is in the pile cannot be said to have intended one.
Conditional wills — ones that say something like “if I do not return from this trip, the following is my will” — are a gray area. Courts generally try to uphold them, but the wording matters. If the condition reads as the reason you were motivated to write a will rather than a true limit on when it applies, most courts will treat it as unconditional and admit it to probate anyway.
What Can Disqualify a Will Even When You Were Eligible
Two challenges come up repeatedly, and both go to whether the will truly reflects what you wanted.
Undue Influence
Undue influence happens when someone in a position of trust or authority uses that position to steer the will’s terms in their own favor. Courts look for three warning signs together: a close or confidential relationship with the person making the will, a substantial benefit flowing to the alleged influencer under that will, and active involvement in arranging or procuring the document. When all three line up, the burden can shift to the beneficiary to prove the will was legitimate.
Common red flags include isolating the person from family, controlling access to information or medical care, rushing preparation of the will, and arranging for the signing to happen at unusual times or places. The more vulnerable the person — through age, illness, or dependency — the more closely courts examine the relationship.
Fraud
Fraud comes in two shapes. Fraud in the execution means the person was tricked about the nature of the document itself, such as being told they were signing a birthday card when it was actually a will. Fraud in the inducement means the person knew they were signing a will but was deceived about the facts that shaped their choices, such as being falsely told a child had died. Either form can invalidate the will or the affected provisions.
Signing a Will the Right Way
Even a person who is eligible and sincere needs to follow execution formalities. These vary by state but generally include three things:
- The will must be in writing. Oral wills are recognized only in very limited circumstances in a small number of states.
- You must sign the will, or someone else must sign it at your direction and in your presence.
- Most states require at least two disinterested witnesses — people who are not beneficiaries — to watch you sign and then sign the will themselves.
Notarization of the will itself is not required in most states. Many states do allow a self-proving affidavit, a notarized statement signed by you and your witnesses confirming the formalities were followed. Attaching one usually spares your witnesses from having to appear in probate court later to confirm the will’s authenticity, which can speed probate considerably.
Handwritten (Holographic) Wills
About half of U.S. states recognize holographic wills, which are handwritten by the person making them. A holographic will is typically valid without witnesses as long as the signature and the key provisions are in the person’s own handwriting. Because these wills lack witness testimony and are often written without legal guidance, they are more vulnerable to challenges over intent, capacity, or unclear language. If you rely on a holographic will, make sure your handwriting clearly spells out what you want to happen with your property.
Citizenship and Where You Live
You do not need to be a U.S. citizen to make a valid will. Non-citizens and undocumented residents can execute a will governing property they own, as long as they meet the standard age and capacity requirements. The right to direct what happens to your property after death is tied to ownership, not immigration status.
Your state of residence determines which laws govern how your will is executed and interpreted. If you own property in more than one state, each state’s laws may apply to the property located there. Most states, however, are flexible about recognizing wills from other jurisdictions, and a will validly executed where you lived at the time of signing is generally honored elsewhere. If you move to a new state after signing, your will usually remains valid as long as it met the requirements of either the old state or the new one. Reviewing it after a major move is still a good idea, especially because spousal inheritance rules differ from state to state.
Changing or Revoking Your Will Later
A will is not a one-time commitment. You can revoke or change yours at any time, as long as you still have the mental capacity to do so. There are two main ways to revoke one:
- Sign a new will that expressly revokes the earlier one, or that contains terms inconsistent with it.
- Physically destroy the original — burning, tearing, or otherwise destroying it — with the intent to revoke. Intent matters here; accidentally damaging a will does not revoke it.
Marriage, divorce, the birth of a child, or a significant change in your finances are all good reasons to pull your will out and review it. A document that matched your wishes five years ago may not match them now, and outdated provisions can create expensive disputes for the people you leave behind.