Any person over the age of 18 who is of sound mind may create a will in Missouri. There are a few requirements, however.
First, a will in Missouri must be in writing. Second, it must be signed by the testator, the person creating the will, or at their direction. Finally, the will must be attested by at least two competent witnesses who sign the will in the testator’s direction. A witness does not have to be over 18, but it is always better to use an adult witness. A Missouri will does not need to be signed on every page.
A will is not invalidated if one of the witnesses is an “interested witness” or a person having a property right or claim against the estate. However, if the interested witness is receiving more than they would receive if the testator died without a will, the interested witness forfeits the stated amount.
Example: Dad is a widower and has a son and a daughter. He has a will drafted that leaves his son 75% of his estate and only 25% of the estate to his daughter. Son is a witness while Dad signs the will and daughter is not a witness. Under the laws of intestacy (dying without a will), son would normally be entitled to half the estate and daughter would be entitled to the other half, since Mom has predeceased Dad and they are the only heirs of the estate. Since son witnessed will, he will forfeit 25% of his inheritance and only received 50%.
Missouri allows self-proving wills. A self-proving will is one that contains an affidavit usually signed by a notary that states, among other things, that the testator was of sound mind when the will was signed, that the signature was provided in the presence of the witnesses, without undue influence and in the presence of the witnesses.
If the will is self-proving, it is considered by a court to be substantial evidence that the testator had capacity and that the will was properly executed. Perhaps more importantly, it shifts the burden of proving that the testator lacked capacity to the party making such a claim.
A will may be revoked by a new will, or if the will is purposely destroyed by the testator.
Terms of a will may be changed by the publication of a new will called a codicil. There is no limit to how many codicils can be drafted, but the testator must have capacity to create a codicil, just as with the original will.