Self-Proving Affidavit for Wills Requirements in Missouri

At a glance

Requirements one by one

Availability and governing law

Section 474.337 creates Missouri's traditional self-proof procedure. The probate code definition of "will" includes a codicil, so the same procedure reaches a codicil. Missouri's electronic-wills act adds § 474.550 and applies to a will of a decedent who dies on or after August 28, 2025 (§ 474.564).

Self-proof remains optional. Section 473.053 supplies the ordinary proof route when a will does not have a valid self-proof certificate.

Who signs or swears

The testator and both witnesses must appear together before the officer and be first duly sworn. Each then makes the required declarations. The statutory form describes their names as already signed to the attached or foregoing will, but it does not give the testator or witnesses separate signature lines on the self-proof certificate. The officer signs the certificate.

This differs from states where three affiants sign a separate affidavit page. In Missouri, the sworn joint appearance and the officer's sealed certification are the operative self-proof acts.

When it may be made

Sections 474.337 and 474.550 both say self-proof may occur at execution or "at any subsequent date." They set no elapsed-time deadline. Because the process requires the testator and witnesses to appear and make their own acknowledgments, the cited sections provide no after-death requester or substitute-affiant route.

Officer, oath and seal

For an ordinary certificate, the officer must be authorized to administer oaths under Missouri law and must sign under official seal. If an otherwise authorized officer has no official seal, § 474.337.2 permits a statement that the officer has no seal and a recital of the facts establishing authority; the statute gives that statement the same effect as a seal.

The remote electronic-will route uses a remote online notary authorized to perform the Missouri act under state or federal law. Section 486.1165 requires a registered electronic signature and a registered electronic notary seal stating the notary's commissioned name, commissioning jurisdiction, title, commission or registration number, and expiration date.

Required recitals and form

The certificate must be substantially, not word-for-word, in the statutory form. The testator declares that the instrument was signed and executed as the last will, that the signature or direction to another signer was willing, and that the will was a free and voluntary act for its stated purposes. Each witness's declaration must establish that the witness signed the will in the testator's presence and hearing. To the witnesses' best knowledge, the testator was at least 18, of sound mind, and under no constraint or undue influence.

The remote form in § 474.550 carries the same substantive recitals and adds that the testator and witnesses personally appeared by remote online means.

Attachment to the will

Section 474.337 requires the officer's sealed certificate to be "attached or annexed to the will." Its form refers to the attached or foregoing instrument. The electronic-will section permits self-proof in that same manner or through its remote online notarial certificate, whose form likewise identifies the attached or foregoing instrument.

Electronic, remote and out-of-state rules

An electronic will may be made self-proved through the ordinary § 474.337 procedure. If fewer than two witnesses are physically in the same location as the testator when the acknowledgments are made, § 474.550 instead permits the remote-online-notary certificate.

Section 474.548.3 adds a separate consequence at execution. If no self-proving affidavit is signed contemporaneously with the electronic will, each witness must be a resident of a state and physically located in a state at signing. A later affidavit may make the will self-proved, but it does not satisfy the statute's condition that avoids this witness-location rule at the original signing.

The remote notary may derive authority from the law of any state or the United States. Sections 474.337 and 474.550 do not separately say that a will's self-proved status under another jurisdiction's law is automatically recognized.

Probate effect and exceptions

For an ordinary written will, § 473.053.1 generally requires at least two subscribing witnesses to be examined and to testify to execution facts. The same subsection expressly says that requirement does not "affect the probate of a self-proved will." The officer's certificate therefore supplies the self-proof route in place of the ordinary two-witness examination.

The cited statutes do not label the certificate conclusive, create an irrebuttable presumption, or state that self-proof prevents a contest. Section 473.053 also preserves the separate rules of evidence for probate in solemn form.

If there is no affidavit

When the subscribing witnesses are alive, competent, and otherwise available, § 473.053.1 requires at least two of them to be examined about facts showing proper execution. If either or both witnesses are dead, physically or mentally unable to testify, or cannot be located, subsection 2 uses the available witness, if any, plus proof of an unavailable witness's handwriting or other available competent evidence.

What trips people up

The witnesses must say they signed the will

The statutory recital is not merely that the witnesses watched the testator sign. It also says each witness, "in the presence and hearing of the testator, signed the will as witness." A certificate that describes only witnessing the testator's signature omits one of the execution facts the officer must certify.

Later self-proof does not rewrite electronic-will execution facts

Missouri permits an electronic will to be made self-proved later. But § 474.548.3 separately looks at whether an affidavit was signed contemporaneously when deciding whether the witnesses had to reside in and be physically located in a state at signing. Later self-proof changes probate proof, not the facts required at the original electronic signing.

Common questions

Do the testator and witnesses sign a separate Missouri affidavit page?

The statutory form does not give them separate signature lines. They appear together, are sworn, and make their declarations; the officer signs and seals the certificate attached or annexed to the will.

Can a Missouri will be made self-proving later?

Yes. Both the paper and electronic sections allow self-proof at any subsequent date, provided the required testator, witnesses, officer, declarations, and certificate are available.

What if the officer has no official seal?

Section 474.337.2 permits an authorized officer with no seal to state that fact and recite the facts establishing the officer's authority. The statute treats that statement as having the same effect as an official seal.

Does self-proof prevent a challenge to the will?

No such bar appears in the cited statutes. Self-proof avoids the ordinary two-witness examination; it does not make the certificate conclusive or displace the separate evidentiary rules for a solemn-form probate proceeding.

Statutes and sources

• Mo. Rev. Stat. § 472.010(30) — will includes codicil: official current text (accessed 2026-08-01)
• Mo. Rev. Stat. § 474.337 — traditional self-proof, joint sworn appearance, certificate form, attachment, seal, and no-seal substitute: official current text (accessed 2026-08-01)
• Mo. Rev. Stat. §§ 474.548.3, 474.550, 474.564 — electronic-will witness location, self-proof and remote-notary form, and applicability: § 474.548, § 474.550, and § 474.564 (accessed 2026-08-01)
• Mo. Rev. Stat. § 486.1165.1–.3 — remote online notarial certificate, electronic signature, and electronic seal contents: official current text (accessed 2026-08-01)
• Mo. Rev. Stat. § 473.053 — ordinary two-witness proof, unavailable- witness evidence, and self-proved-will exception: official current text (accessed 2026-08-01)