Who this is for: Missouri adults writing a will, or checking one they already signed. What it covers: every requirement in Missouri's Probate Code for a valid Last Will and Testament, the electronic will law that took effect in 2025, and the mistakes that sink wills in probate court. Why it matters: Missouri has no harmless-error rule. Miss one formality and the court treats you as if you never wrote a will. Patrick Nolan is an estate planning attorney at Nolan Law Firm in Kirksville, Missouri.
Quick Answer: Under RSMo 474.320, a Missouri will must be in writing, signed by the testator (or by someone else at the testator's direction and in the testator's presence), and signed by at least two competent witnesses in the testator's presence. The testator must be 18 or older, or an emancipated minor, and of sound mind. A notary isn't required. A notarized self-proving affidavit lets the will into probate without calling the witnesses. Since August 28, 2025, Missouri also accepts electronic wills that meet the same basic test.
Who can make a will in Missouri
Section 474.310 sets two conditions: you're of sound mind, and you're 18 or older. A minor can also make a will if a court has emancipated them, or they've married or entered active military duty.
Sound mind is a low bar, and it's measured at the moment you sign. You need to understand what you own, who your family is, and that you're signing a document that decides where your property goes when you die. Old age doesn't disqualify you. Neither does a diagnosis. A person with early dementia can sign a valid will on a good day, and a judge looks at that day, not the month before or after.
What a Missouri Last Will and Testament has to have
Four things, and Missouri wants every one of them.
- Writing. Typed or handwritten, on paper or, since 2025, as an electronic record. Oral wills are almost never valid; more on that below.
- Your signature. If you can't physically sign, someone else may sign your name for you, but only in your presence and at your direction. Put that person in the room with the witnesses, and don't use one of the witnesses to do it.
- Two witnesses. At least two competent people sign the will in your presence. They should watch you sign, or hear you acknowledge the signature as yours.
- One sitting. The statute doesn't spell out an order, but the safe practice is everyone in the same room at the same time: you, both witnesses, and the notary if you're self-proving the will.
There's no magic language. A will doesn't need a seal, a lawyer's letterhead, or the words "being of sound mind." It needs those four things and clear instructions.
Pick witnesses who get nothing
Any person competent to testify can witness a Missouri will, and a will isn't void because a beneficiary signed as a witness. The beneficiary pays for it. Under Section 474.330, an interested witness loses anything the will gives them beyond what they'd have inherited with no will at all. That forfeiture doesn't apply if two other witnesses with no interest also signed.
Being named executor doesn't make a witness "interested." Neither does being owed money by the estate. The rule bites when the witness takes something under the will.
Don't hand the pen to your daughter because she drove you to the signing. Use two adults who inherit nothing, and the question never comes up.
The self-proving affidavit
A self-proved will gets into probate on paper. Without one, the court may need the witnesses, or proof of their handwriting, years after the signing, when one has moved to Arizona and the other has died.
Section 474.337 lets you, and both witnesses, swear before a notary that you declared the document your will, signed it willingly, and that the witnesses believed you were 18, of sound mind and under no undue influence. The notary's certificate is attached to the will. Under Section 473.065, a will with that certificate is admitted to probate "without further proof."
It's optional. It's also one more page and ten more minutes at the signing table. Do it. A self-proving affidavit won't stop a contest over capacity or undue influence. It does end any argument over whether the will was signed properly.
Handwritten wills need witnesses too
Some states accept a will written entirely in your own hand with no witnesses. Missouri doesn't. A handwritten will is held to the same Section 474.320 test as a typed one. The letter in the desk drawer that says "I want Sarah to have the farm," signed but never witnessed, isn't a will in Missouri, however clear it is.
Oral wills: a $500 exception
Section 474.340 allows a spoken will in one narrow case. The person must be in imminent peril of death, from illness or otherwise, and must die from that peril. They declare the will before two disinterested witnesses; one of them writes it down within 30 days; it's offered for probate within six months. Even then it can pass only personal property worth $500 or less, and it can't change a written will.
For practical purposes, Missouri wills are written wills.
Electronic wills became valid in 2025
The Missouri Electronic Wills and Electronic Estate Planning Documents Act, Sections 474.540 to 474.564, took effect August 28, 2025, and applies to the will of anyone who dies on or after that date. An electronic will is a will for all purposes.
Under Section 474.548, an electronic will must be readable as text when it's signed and stay readable afterward. The testator signs it, or someone signs for the testator in the testator's physical presence and at their direction. At least two witnesses sign within the testator's physical or electronic presence, after watching the signing or hearing the testator acknowledge it. That means a witness can attend by live video. Section 474.550 supplies a self-proving affidavit for electronic wills, which can be done with a remote online notary.
A typed document you emailed to yourself still isn't a will. An electronic will has to go through a signing with witnesses; it's a different way to sign, with the same rules about who has to be there.
Wills signed in another state
If you moved to Missouri with a will signed somewhere else, Section 474.360 honors it if it was executed under Missouri law, under the law of the place where it was signed, or under the law of the place where you lived at signing or at death. Even a valid out-of-state will may not fit a Missouri estate. Elective share rules, the personal representative rules below and Missouri beneficiary deeds can all change how the plan works here. Have it reviewed after the move.
Changing or revoking your will
Under Section 474.400, you revoke a will, or part of one, in two ways: a later written will, or burning, tearing, cancelling or obliterating the original yourself, or having it done in your presence at your direction.
Notes in the margin don't count. In Oliver v. Union National Bank (1974), a Missouri court refused to enforce names struck and shares rewritten on a signed will; the will stood as originally signed. If you want a change, sign a codicil with the same formalities as a will, or sign a new will that revokes the old one. For anything more than a small change, a new will is cleaner.
When life changes your will for you
Divorce. Under Section 474.420, a divorce after you sign your will revokes the gifts to your former spouse, and the will reads as if that spouse died on the date of the divorce. The statute speaks to gifts, not to every role your ex holds in the will. Update it.
Marriage. Marrying doesn't revoke your will, and you can't write a new spouse out of it. Under Section 474.160, a surviving spouse can take an elective share instead of what the will leaves: one-half of the estate if you have no descendants, one-third if you do. A valid prenuptial or postnuptial agreement is the usual way around it.
A new child. Under Section 474.240, a child born or adopted after you sign, and left out of the will, takes what they'd have received with no will at all. The exceptions: the will shows the omission was intentional; you already had a child when you signed and left substantially everything to the omitted child's other parent; or you provided for the child outside the will in place of a gift in it. If you mean to leave a child out, say so in the will, in plain words.
What your will can't control
A will governs probate property: assets in your name alone with no beneficiary named. It doesn't control life insurance, retirement accounts, payable-on-death accounts, joint accounts with right of survivorship, property in a funded living trust, or real estate passing by a beneficiary deed. Those pass by contract or by deed, whatever the will says.
That's why the beneficiary forms matter as much as the will. If the will leaves everything to your three children equally and the IRA names only one of them, the one gets the IRA.
Where to keep the original
The probate court wants the original, signed will. Keep it in a fire-resistant safe, with your attorney, or on deposit with the court. Section 474.510 lets you deposit your will, sealed, with the probate division of a circuit court during your lifetime; only you, or someone you authorize in writing, can take it back out. A safe deposit box works if someone besides you can get into it.
Tell your personal representative where it is. After death, Section 473.050 requires the will to be presented to the probate division. A will that isn't presented within six months after the first published notice of letters, or within one year after death if no notice was published, is barred from probate for good.
Naming the right personal representative
Your will names the person who runs the estate. Section 473.117 disqualifies anyone under 18, a person of unsound mind, and a person under legal disability from a criminal conviction, among others. A nonresident can serve but must file a designation naming a Missouri resident to accept service for them. Name an alternate. People decline, move, and die before you do.
If you have children under 18, the will is also where you name their guardian. The court still decides what's best for the child, but it starts with your choice. More on that in naming a guardian for your minor children.
If the will fails
A will that misses Section 474.320 doesn't get partial credit. Your estate passes under Missouri's intestate succession statute, the same as if you'd never written one. The order runs spouse and descendants, then parents and siblings, then more distant relatives; your best friend, your church and your stepchildren get nothing.
A will that meets the formalities can still be challenged for lack of capacity, undue influence or fraud. Under Section 473.083, a will contest must be filed within six months after the will is admitted or rejected, or six months after the first publication of notice of letters, whichever is later. Disinterested witnesses, a self-proving affidavit and a signing your family wasn't steering are the best defense.
Getting it signed right
You don't need a lawyer to make a Missouri will. You do need every formality, and that's where homemade wills fail: one witness, a beneficiary witness, a missing signature page, an online form built for another state.
Nolan Law Firm prepares wills as part of every estate plan, at a flat fee quoted up front, signed in one appointment at our Kirksville office. Reserve a meeting. If you're weighing a will against a trust, start with Will or Trust.
Frequently Asked Questions: Missouri Will Requirements
What makes a will legally valid in Missouri?
Under RSMo 474.320, the will must be in writing, signed by the testator or by another person at the testator's direction and in the testator's presence, and signed by at least two competent witnesses in the testator's presence. Under RSMo 474.310, the testator must be of sound mind and 18 or older, or an emancipated minor.
Does a Missouri will need to be notarized?
No. Notarization isn't required for the will to be valid. A notary is needed only for the optional self-proving affidavit under RSMo 474.337, which lets the will be admitted to probate without further proof from the witnesses.
Are handwritten wills valid in Missouri?
Only if they're witnessed. Missouri doesn't recognize unwitnessed handwritten wills. A handwritten will must meet the same requirements as a typed will: the testator's signature and two witnesses signing in the testator's presence.
Are electronic wills valid in Missouri?
Yes, for anyone who dies on or after August 28, 2025. Under RSMo 474.540 to 474.564, an electronic will must be readable as text, signed by the testator, and signed by at least two witnesses in the testator's physical or electronic presence. It can be self-proved under RSMo 474.550.
Can a beneficiary witness a Missouri will?
Yes, but under RSMo 474.330 a beneficiary-witness forfeits anything beyond what they would have inherited without a will, unless two other disinterested witnesses also signed. Use two witnesses who inherit nothing.
How do I change or revoke a Missouri will?
Sign a new will or a codicil with the same formalities as the original, or destroy the original with the intent to revoke it. Under RSMo 474.400, handwritten changes on a signed will have no effect. Divorce revokes gifts to a former spouse under RSMo 474.420.
How long do I have to contest a will in Missouri?
Under RSMo 473.083, a will contest must be filed within six months after the will is admitted to or rejected from probate, or six months after the first publication of notice of letters, whichever is later.