Power of Attorney: Definition and How It Works in California

By Eric Ridley, attorney, Ridley Law. Updated September 2026.

A power of attorney is a document giving a named agent authority to act for another person in financial or legal matters, either immediately or on the occurrence of a stated event.

How it works in California

Prob. Code, § 4022 defines a power of attorney as a written instrument, executed by a person with the capacity to contract, that grants authority to an attorney-in-fact, and notes that a power of attorney may be durable or nondurable. Setting up a power of attorney means choosing an agent, deciding what authority to give them, and deciding when that authority starts.

Most estate planning documents use a durable power of attorney. Prob. Code, § 4124 sets out the durability language: the power of attorney isn’t affected by the principal’s later incapacity. Without that language, an ordinary power of attorney ends the moment the person who signed it becomes incapacitated, which is exactly when a family usually needs it most.

Why it matters

A power of attorney is often the only document that lets someone else pay bills, manage accounts, or handle property for a person who can no longer do it themselves, without going to court. Say a parent has a stroke and can no longer manage their own finances. A child named as agent under a durable power of attorney can step in immediately to pay the mortgage and manage accounts. Without that document, the family may have to open a conservatorship, a court process that takes longer and costs more.

Common mistakes

Signing a power of attorney that isn’t durable, so it lapses at the exact moment it’s needed. Naming an agent without naming a backup, so there’s nobody to step in if the first choice can’t or won’t serve. Waiting until after a diagnosis to sign one, when the person may no longer have the capacity to execute it.

Related terms

• Advance healthcare directive: the companion document that covers medical decisions instead of financial ones.
• Conservatorship: the court process a family may need if nobody holds a valid power of attorney when incapacity happens.
• Durable power of attorney: a power of attorney drafted to survive the principal’s incapacity, which is what most estate plans use.
• Springing power of attorney: a power of attorney that doesn’t take effect until a stated event occurs, rather than immediately.

Part of the California estate planning glossary. For the full treatment, see CA Power of Attorney Guide for Families.