Will Execution Requirements in Missouri

At a glance

Requirements one by one

Governing law

Missouri now has two execution tracks. Sections 474.310 through 474.360 govern traditional written wills. The Electronic Wills and Electronic Estate Planning Documents Act, §§ 474.540 through 474.564, took effect August 28, 2025 and applies to wills of decedents dying on or after that date. Section 474.544 makes an electronic will a will for all purposes unless the newer act modifies the ordinary rule (§ 474.544). The decedent-death applicability date comes from § 474.564.

Minimum age and capacity

Section 474.310 permits a will by a person of sound mind who is at least 18 or by a minor emancipated through adjudication, marriage, or entry into active military duty. The 2025 electronic-wills act changes the medium and ceremony, not that capacity rule.

Writing and signature

A traditional will must be in writing and signed by the testator or by someone acting at the testator's direction and in the testator's presence. An electronic will must be a record readable as text when signed and remain accessible as text for later reference. It is signed by the testator or by another individual in the testator's name, physical presence, and direction.

Witnesses required

Both routes require at least two witnesses. Traditional witnesses subscribe their names in the testator's presence under § 474.320. Electronic witnesses sign after witnessing the signing or the testator's acknowledgment and may act in the testator's physical or electronic presence. “Electronic presence” means real-time, live interactive audio-video communication allowing observation, interaction, and communication.

Section 474.330's competency and interested-witness rules still apply. A gift to an interested witness can be reduced to the intestate-share amount unless two disinterested witnesses also attest.

Notarization and self-proving

Notarization is not part of either basic validity ceremony. It is used for optional self-proof. A traditional will uses § 474.337. An electronic will may use the same method or, when fewer than two witnesses are physically in the same location as the testator for the acknowledgments, a remote online notary and the certificate described in § 474.550.

Handwritten wills

Missouri still has no unwitnessed holographic-will exception. A handwritten document can be a traditional will if it satisfies § 474.320, but handwriting alone does not replace the two witnesses. The electronic-will act is a separate two-witness route, not a holographic exception.

Electronic and remote wills

Missouri permits both. Section 474.548 requires a readable electronic record, the testator's compliant signature, and signatures from at least two witnesses in physical or electronic presence. Extrinsic evidence may establish that the testator intended the record to be the electronic will.

The law also recognizes an electronically executed will made under qualifying law of the signing jurisdiction, the testator's domicile, or the testator's residence under § 474.546. Remote witnessing still requires the live interactive audio-video relationship defined in § 474.542; asynchronous email or recorded video is not that definition.

Harmless error and foreign execution

Missouri has no general statute admitting a defective will merely because the testator's intent is clear. The cross-border rules are different: § 474.360 recognizes a traditional written will executed under listed Missouri, signing- place, domicile, abode, or nationality law, and § 474.546 supplies the electronic counterpart for signing-place, domicile, or residence law.

What trips people up

The electronic-wills act did not remove the two-witness requirement. It changed the record and presence rules: the will may be electronic and witnesses may use live interactive audio-video presence, but the testator and two witnesses still must complete the statutory ceremony.

Self-proof is optional but the witness-location overlay matters. Section 474.548(3) adds state-residency and physical-location language when no self-proving affidavit is signed contemporaneously. Remote execution should be planned with the self-proving route, not improvised after signatures are applied.

Common questions

Can my witnesses join by live video?

Yes, for a compliant electronic will. The communication must be real-time and interactive so the participants can observe and communicate with one another, and the witnesses sign after seeing the signing or acknowledgment.

Does an electronic will need a remote notary?

Not for basic validity. A remote online notary is one way to make the electronic will self-proved when fewer than two witnesses are physically with the testator for the acknowledgments.

Can I handwrite a will with no witnesses?

No. Handwriting does not create an exception to Missouri's two-witness rule. A handwritten will may qualify only if it satisfies the ordinary execution statute or another applicable law recognized by § 474.360.

Statutes and sources

• Mo. Rev. Stat. §§ 474.310, 474.320, and 474.330 — capacity, traditional signature and witness ceremony, witness competency, and interested-witness effect. § 474.310, § 474.320, and § 474.330 (accessed 2026-08-01).
• Mo. Rev. Stat. §§ 474.337 and 474.360 — traditional self-proof and cross-border execution. § 474.337 and § 474.360 (accessed 2026-08-01).
• Mo. Rev. Stat. §§ 474.542, 474.544, and 474.546 — electronic presence, signing definitions, full will status, and foreign electronic execution. § 474.542, § 474.544, and § 474.546 (accessed 2026-08-01).
• Mo. Rev. Stat. §§ 474.548, 474.550, and 474.564 — electronic signature and witness ceremony, remote self-proof, and applicability. § 474.548, § 474.550, and § 474.564 (accessed 2026-08-01).