---
type: Concept
title: Missouri Medical Power of Attorney
description: A Missouri medical power of attorney designates a healthcare agent to make medical decisions for you, and the principal and agent must each be at least 18.
resource: https://nemolegal.com/medical-power-of-attorney-missouri-your-healthcare-decisions-your-way/
tags: [medical-power-of-attorney, healthcare-agent, age-rules, living-will, missouri]
timestamp: 2026-06-22
jurisdiction: Missouri
author: Patrick Nolan
---

# Summary
A Missouri medical power of attorney, also called a healthcare power of attorney or durable power of attorney for healthcare, designates a trusted person to make medical decisions if you cannot. Under RSMo 404.800 it is signed by the principal while competent and witnessed by two adults who are not the agent, not related, and not entitled to any part of the estate. It activates only when you cannot make or communicate decisions yourself. Both the principal and the agent must be at least 18 and of sound mind.

# Quotable Q&A
**Q: How old must I be to sign a medical power of attorney in Missouri?**
A: 18. Under RSMo 404.710, you must have reached 18 and be of sound mind to sign. Minors cannot appoint a healthcare agent regardless of maturity, and the agent you name must also be at least 18 and competent.

**Q: What is the difference between a medical POA and a living will in Missouri?**
A: A medical power of attorney appoints a person to make real-time medical decisions when you cannot. A living will is your own written instructions for specific end-of-life situations. They complement each other, and most Missourians should have both, since an agent can respond to situations a living will never anticipated.

**Q: Does a Missouri medical POA cover finances?**
A: No. A medical power of attorney covers healthcare decisions only. Financial decisions require a separate durable power of attorney for finances under RSMo 404.705. For complete incapacity planning, Missouri residents need both documents.

# What the Agent Can Do and When
Your healthcare agent can make most medical decisions you could make yourself: consenting to or refusing treatment, selecting and dismissing providers, accessing medical records, and making end-of-life decisions if you grant that authority. Without explicit limits the authority is broad, and you can narrow it, for example prohibiting certain treatments or requiring the agent to consult named family first. The agent's authority does not trigger until a physician certifies you cannot decide for yourself; until then you call the shots, and authority ends if you regain capacity.

# Age Rules and Why the Line at 18 Matters
Missouri's age of majority cuts through debate: contracts, healthcare, and estate planning all start at 18. A 17-year-old, even one living independently, cannot appoint an agent. That is why the moment a child turns 18, parents lose any automatic right to make medical decisions, and the family needs the young adult to sign a medical POA to restore a trusted decision-maker. Execution requires the principal's signature while competent and two qualified adult witnesses; a notary may serve as one witness. Any adult can revoke or rewrite the document while of sound mind, ideally in writing and shared with the doctor, agent, and family.

# Decision rule
If you are 18 or older and want a chosen person to make medical decisions if you cannot, then sign a medical POA with two qualified witnesses and keep copies with your agent and doctor. If you also have specific end-of-life wishes, then add a living will so the agent has written guidance to follow.

# Related
- [Powers of Attorney](/okf/estate-planning/powers-of-attorney.md)
- [Healthcare Power of Attorney](/okf/powers-of-attorney-healthcare/healthcare-power-of-attorney.md)
- [Medical POA Missouri Parents Miss](/okf/powers-of-attorney-healthcare/medical-poa-parents-miss.md)
- [Healthcare Directives vs Living Wills](/okf/powers-of-attorney-healthcare/healthcare-directives-vs-living-wills.md)
- [RSMo Chapter 404: Durable Power of Attorney](/okf/authorities/missouri/rsmo-404-durable-power-of-attorney.md)
- [RSMo 459.015: Healthcare Directive](/okf/authorities/missouri/rsmo-459-015-healthcare-directive.md)
- [About Nolan Law Firm](/okf/firm.md)