Missouri Revised Statutes Title XXXI. Trusts and Estates of Decedents and Persons Under Disability § 473.380. Claims, form and verification--claim to be established by evidence

1. No claim other than for costs and expenses of administration shall constitute a claim against an estate unless it is in writing, stating the nature and amount thereof, if ascertainable, and is signed by the claimant, or by some person for him who has knowledge of the facts, stating that to the best of his knowledge and belief he has given credit to the estate for all payments and offsets to which it is entitled and that the balance claimed is justly due.

2. If a claim is founded on a written instrument, the original or a copy thereof with all endorsements shall be attached to the claim. The original instrument shall be exhibited to the personal representative, upon demand, unless it is lost or destroyed, in which case its loss or destruction shall be stated in the claim.

3. The statement of claim herein required shall not be received as any evidence of the claim but such claim shall be established by competent evidence before it is paid or adjusted.

4. Upon the filing of any claim, the probate clerk shall immediately send a copy of the claim to the personal representative or his attorney.