What Makes a Will Legal?

Here are three key requirements that make a will legal.

1. Mental capacity

For a will to be valid, the testator must be of sound mind. Generally, this means the testator must meet the following criteria:

• Age. Be an adult, typically 18 or older
• Awareness. Be conscious and aware of what they are doing
• Understanding. In some states, comprehend how their assets are being distributed

Challenges to a last will often involve allegations of a testator's lack of capacity to execute the document. Such arguments could include that the testator was under duress, threats, fraud, or coercion, and didn't draw up the document under their own free will.

2. Signatures

To be valid, a will must be signed by the testator. Deathbed signatures by a testator can be just as valid as any other signatures, provided the person signing the will has the capacity to do so.

In addition to the testator's signature, most states require witnesses who meet these criteria:

• At least 18 years old
• Present when the testator signs the will
• Two witnesses are required in most states, but a few require three

Getting a last will witnessed, therefore, usually entails a meeting with a small group of people, including the testator and witnesses.

Who cannot serve as a witness?

The person named as executor in the will does not have to sign the will for it to be valid. In fact, some jurisdictions specifically require the signatures of disinterested witnesses. In many instances, the executor of a will is also a named beneficiary, which would make them an interested party and ineligible to be one of the witnesses.

Handwritten (holographic) wills

A holographic will is one that is handwritten by the testator rather than typed or printed. These wills are recognized in roughly half of U.S. states, including California, Texas, and New Jersey. When valid, the material provisions—meaning the key terms regarding who gets what—must be in the testator's own handwriting and signed by them.

The witness requirements for holographic wills vary significantly by state. Some states, like New Jersey, accept holographic wills without any witnesses at all, while others require the same witness formalities as typed wills. States that don't recognize holographic wills—such as Florida, Illinois, and New York—will not honor a handwritten will regardless of how carefully it was drafted.

If you're considering a handwritten will, be aware that making typed additions or changes to the document can create validity issues. Courts may struggle to determine which portions of the will should be enforced. Check your state's specific laws before relying on a holographic will, as an unrecognized handwritten will could leave your wishes unenforceable.

3. Notary public

A will does not need to be notarized to be valid. However, this extra step can be helpful during probate, the court-supervised process of distributing the property of a deceased person. A "self-proving affidavit" signed before a notary could help prove your will is valid without requiring witnesses to testify in court.

To execute this affidavit, you and your witnesses must appear in front of a notary public to sign this sworn statement. Some states consider this type of affidavit as convincing proof of a will's validity.

Do you need an attorney to create a will?

No state requires attorney involvement for a will to be legally valid. You can create a DIY will yourself, use an online service, or work with an estate planning attorney—all three approaches can produce a valid will as long as the legal requirements are met.

That said, attorney assistance is often advisable in certain situations. Consider consulting a lawyer if you have a complex estate with multiple properties or business interests, a blended family with children from previous marriages, significant assets that may trigger estate tax concerns, or anticipate challenges to your will from disgruntled family members. An attorney can also help you coordinate your will with other estate planning tools like trusts.

Online legal services offer a middle ground, with guided templates and legal resources at a lower cost than hiring an attorney directly. Whether you have an estate planning attorney prepare your will, use an online service, or draw up a homemade will yourself, the requirements of a valid will apply.

State-specific will requirements

While the basic requirements for a valid will are consistent across the country—mental capacity, proper signatures, and witnesses—states have important variations that can affect whether your will holds up in court.

Here are some key differences to be aware of:

• Number of witnesses. Most states require two witnesses, but Vermont requires three.
• Holographic wills. States like California, Texas, and New Jersey recognize handwritten wills without witnesses, while Florida, New York, and Illinois do not accept them under any circumstances.
• Self-proving affidavits. While all states accept self-proving affidavits to streamline probate, the specific language and notarization requirements vary. Some states have statutory forms that must be followed exactly.
• Electronic wills. A growing number of states, including Florida, Arizona, and Nevada, now permit electronic wills with digital signatures, though requirements for remote witnessing differ.

Some states also offer unique features. New Jersey, for example, maintains a Will Registry where you can register your will's location to help ensure it's found after your death. Florida requires that any will signed outside the state must still meet Florida's requirements if you're a Florida resident at the time of death.

Because these variations can significantly impact your estate plan, always verify your state's specific requirements before finalizing your will. If you own property in multiple states, you may need to ensure your will satisfies the requirements of each jurisdiction.

Common mistakes that can invalidate your will

Even well-intentioned wills can be thrown out by courts if they contain certain errors.

• Using interested witnesses: If a witness is also a beneficiary named in the will, their signature may be invalid in many states. Always use disinterested witnesses who have nothing to gain from the will.
• Improper witness procedures: All witnesses typically must be present simultaneously when the testator signs. Having witnesses sign at different times or locations can invalidate the will.
• Missing or incomplete signatures: Forgetting to sign the will, or signing in the wrong place, is more common than you might think—especially with multi-page documents.
• Unclear or ambiguous language: Vague descriptions like "my jewelry goes to my children" without specifying which pieces go to whom can lead to disputes and potential invalidation of those provisions.
• Making handwritten changes after signing: Crossing out provisions or writing in changes after the will has been executed doesn't work. Any modifications require a formal codicil or an entirely new will with the same signing formalities.
• Failing to meet state-specific requirements: Moving to a new state and assuming your old will still works can be risky. Some states have requirements that your previous state didn't have.
• Not updating after major life changes: Divorce, remarriage, births, deaths, and significant asset changes should trigger a will review. Some states automatically revoke provisions for ex-spouses, but others don't.

Many of these errors connect back to the mental capacity requirement as well. If someone successfully argues that you were under undue influence or didn't understand what you were signing, even a technically perfect will can be set aside.

How to verify your will is valid

Whether you're reviewing your own will or examining one left by a deceased loved one, a systematic check can help confirm its validity. Courts examine these same elements during probate, so catching issues early can prevent problems later.

Use this checklist to verify a will meets legal requirements:

• Testator age and competence. Confirm the person was at least 18 years old and of sound mind when they signed. Look for any evidence of cognitive impairment, undue influence, or duress at the time of signing.
• Written document. The will must be in writing. Video wills and oral wills are not valid in most states, even if they clearly express the testator's wishes.
• Testator signature. Verify the testator signed the document. The signature should appear where your state requires it—usually at the end of the will.
• Witness signatures. Count the witness signatures and confirm they meet your state's requirements (typically two disinterested adults). Check that witnesses weren't beneficiaries.
• Self-proving affidavit. If present, verify the notarization is complete. While not required for validity, a self-proving affidavit significantly streamlines the probate process.
• State-specific requirements. Review your state's particular rules, especially if the will was created in a different state or involves holographic provisions.

During probate, courts conduct this same analysis. If all elements are satisfied, the will is admitted to probate and the executor can begin distributing assets. If questions arise about validity, the court may require witness testimony or additional evidence.

When in doubt, consider having an estate attorney review the will. This is especially important for older wills that may have been drafted under different state laws, or for wills where you suspect potential challenges from other family members. A professional review can identify weaknesses before they become courtroom battles.

Make sure you meet all of your jurisdiction's requirements—or you risk your will being just another piece of paper.

Michelle Kaminsky, J.D., contributed to this article.