The correct way to sign as a power of attorney is to make clear on the page that you are signing on someone else’s behalf, not your own. That means three elements appear together: the principal’s name, your signature, and a label identifying your role, such as “Attorney-in-Fact,” “Agent,” or “POA.” Sign without those elements and you can end up personally on the hook for a contract you thought you were signing for someone else.
The Two Accepted Signature Formats
Two formats are widely accepted across the United States, and both do the same job: they show that the principal is the party to the transaction and you are only the signer.
The first format leads with the principal’s name, adds the word “by,” and follows with your signature and title:
[Principal’s Name], by [Your Name], Attorney-in-Fact
The second leads with your name and title, then names the principal:
[Your Name], Attorney-in-Fact for [Principal’s Name]
Either works in most settings. Some banks, title companies, and government offices prefer one over the other, so ask before you sign if it’s your first time dealing with that institution. “Agent,” “POA,” or “Power of Attorney” can be substituted for “Attorney-in-Fact” without changing the legal effect.
Worked Examples
Say John Smith has appointed Jane Doe as his agent. On a contract signed for John, the signature block should look like one of these:
John Smith, by Jane Doe, Attorney-in-Fact
(Jane Doe’s handwritten signature)
Or:
(Jane Doe’s handwritten signature)
Jane Doe, Attorney-in-Fact for John Smith
Either version tells anyone reading the document that Jane signed in a representative capacity, and neither leaves room to argue she signed for herself.
What Goes Wrong If You Sign It the Wrong Way
Agency law draws a hard line between signing as a disclosed representative and signing without that disclosure. Two mistakes come up again and again.
Signing only your own name is the more dangerous one. If you put just your signature on a nursing home admission agreement, a lease, or a loan document, with no reference to the principal, the other party has every reason to treat you as the responsible party. Under longstanding agency principles, an agent who fails to disclose both the principal’s identity and the representative relationship can be held personally liable on the contract. Creditors can then come after your assets for a debt you intended to create on someone else’s behalf.
Signing only the principal’s name creates the opposite problem. Writing John Smith’s signature without identifying yourself as the authorized signer looks, to anyone reviewing the document later, indistinguishable from a forged signature. You may have full legal authority to act, but you’ve removed the evidence that separates an authorized signing from an unauthorized one. Agents who do this sometimes face uncomfortable questions from banks, regulators, or law enforcement.
The correct format solves both. It binds the principal, protects you, and leaves a paper trail showing the POA was used.
Signing in Specific Situations
The core format doesn’t change, but certain transactions add their own requirements.
Checks and Bank Transactions
Writing checks is probably the most common thing an agent does, and banks can be picky. The standard approach is to write the principal’s name on the signature line, followed by “by,” your signature, and “POA.” A check drawn from John Smith’s account would read: John Smith, by Jane Doe, POA.
Before you write the first check, visit the bank in person with the POA document and a photo ID. Most banks will copy the POA for their files, and some will add you as an authorized signer on the account. Each bank has its own intake process. Walking up to a teller cold with a POA and no prior setup is a reliable way to be turned away.
Deeds and Other Real Estate Documents
Signing a deed, mortgage, or other recorded document for the principal usually takes two extra steps beyond the signature format. Your signature typically needs to be notarized, just as the principal’s would be. And many jurisdictions require the POA document itself to be recorded with the county recorder’s office where the property sits. If the POA isn’t on file, the title company or recorder may reject the deed. Handle both well before closing.
Medical and Healthcare Decisions
A healthcare power of attorney, sometimes called a healthcare proxy or medical POA, is a separate document from a financial POA. Holding a financial POA does not give you authority to make medical decisions or sign consent forms for treatment, and the reverse is also true. Before signing anything at a hospital or doctor’s office, confirm that your POA document actually covers healthcare decisions. Facilities will ask to see it and often photocopy it for the patient’s file.
What You Cannot Sign at All
Even a broad, general power of attorney has limits. Certain acts are considered too personal to delegate, no matter what the document says:
- Voting. Only the principal can cast their ballot. An agent’s role is limited to administrative help, such as requesting an absentee ballot for a qualifying principal.
- Wills and codicils. An agent cannot sign a will on the principal’s behalf. Estate planning documents require the principal’s own signature.
- Marriage. Wedding vows and marriage license applications cannot be delegated.
- Oaths and affidavits. Sworn statements require the personal participation of the person taking the oath.
Signing any of these for your principal doesn’t just fail to bind the principal. It can expose you to legal consequences for acting beyond your authority.
When Your Authority to Sign Ends
Signing authority is not permanent, and several events shut it down, sometimes instantly:
- Death of the principal. A power of attorney ends the moment the principal dies. The executor or personal representative of the estate then takes over, and anything you sign after that point is invalid.
- Revocation. The principal can revoke your authority at any time, as long as they have the mental capacity to understand what they’re doing. Revocation should be in writing, signed, and ideally notarized. Until you receive actual notice of revocation, actions you take in good faith may still be valid.
- Expiration date. Some POA documents include an end date. After it passes, your authority is gone.
- Incapacity of the principal, for non-durable POAs only. A standard, non-durable power of attorney ends automatically if the principal becomes incapacitated. A durable POA is designed to survive incapacity. If you aren’t sure which type you hold, look in the document for language like “this power of attorney shall not be affected by the subsequent disability or incapacity of the principal.” That is the hallmark of a durable POA.
If your authority has ended for any reason, signing a document under the old POA can expose you to liability for acting without authorization. When in doubt, consult an attorney before signing.
A Pre-Signing Checklist
A few questions to run through before putting pen to paper:
- Does this fall within my authority? Read the POA. A financial POA does not let you sign medical consent forms, and vice versa. If the document is limited to specific transactions, stay inside those limits.
- Is the POA still in effect? Confirm the principal is alive, has not revoked the document, and the POA has not expired.
- Do I have the document with me? Always carry a copy of the executed POA. Third parties will ask to see it.
- Am I using the right format? Principal’s name, your signature, your title. Every time.
- Am I keeping a record? Note the date, the document signed, and the purpose, and file copies.
The format itself takes five seconds to learn. The discipline around it, carrying the document, checking your authority, keeping records, and asking institutions about their preferences, is what separates agents who never run into problems from those who do.