To sign a letter on behalf of someone else, use one of three standard formats: p.p. (from the Latin per procurationem) for formal correspondence, By: for contracts and financial documents, or for for routine business letters. In every case, the format has to make two things clear to the reader: whose letter it is, and who actually put pen to paper. Get that right and the signature does its job. Get it wrong and you can create real confusion about who is bound by the document, or in the worst case, expose yourself to personal liability.
The P.P. Format for Formal Letters
“P.p.” is short for the Latin per procurationem, meaning “through the agency of.” It is the traditional convention for formal correspondence where the principal has composed or authorized the letter and someone else is signing it in their absence.
The correct layout puts the principal’s name first, followed by “p.p.” and then the signer:
Jane Smith
p.p. Alex Johnson
[Alex Johnson signs here]
People frequently reverse this and put the signer’s name on top. The traditional order runs principal, then p.p., then signer, because the point is to show the reader at a glance that Jane Smith is the author and authority behind the letter while Alex Johnson executed the signature with her permission.
The “By” Format for Contracts and Financial Documents
The “By” format shows up most often in contracts, financial paperwork, and formal legal correspondence. The principal’s name is typed on the signature line, and the word “By:” introduces the representative who actually signs:
Jane Smith
By: ___________________
Alex Johnson, Authorized Representative
This layout makes the legal relationship explicit. Jane Smith is the party bound by the document. Alex Johnson is the person executing it on her behalf. Financial institutions and law firms tend to prefer this format because it creates a clean record of who did what.
The “For” Format for Routine Correspondence
For everyday business letters, memos, and internal communications, the simplest approach is to sign your own name and add “for” followed by the other person’s name and title:
Alex Johnson
for Jane Smith, Director of Operations
The “for” format signals that Alex isn’t claiming to be Jane. It is the least formal of the three options and isn’t appropriate for contracts or legal documents, but for an ordinary business letter it gets the job done cleanly.
When You Actually Need Written Authorization
Not every signature on someone else’s behalf requires a legal document. If your manager asks you to sign a routine office letter while they’re traveling, a verbal or email request is usually enough. The letter itself carries no legal obligation beyond ordinary business communication, so the stakes are low and informal permission works fine.
The calculus changes completely when the document creates legal or financial obligations. Contracts, real estate deeds, financial account transactions, tax filings, and medical consent forms all bind the person whose name appears on them. For these, you need written authorization that matches the document’s significance. A power of attorney is the standard instrument for most legal and financial matters. Some contexts require specialized authorization, like a healthcare proxy for medical decisions or a board resolution for corporate signatories.
Signing a binding document without any authorization is where people get into serious trouble. At a minimum, the signature is legally ineffective and the transaction can be voided. Beyond that, the unauthorized signer can be held personally liable on the document itself. In serious cases, signing someone else’s name without permission constitutes forgery, which is a criminal offense in every state. Penalties vary by jurisdiction but can include felony charges, substantial fines, and prison time. Even well-intentioned unauthorized signing can trigger these consequences, so when in doubt, get the authorization in writing before you pick up the pen.
Signing Under a Power of Attorney
A power of attorney is a written document in which one person (the principal) grants another (the agent, sometimes called an attorney-in-fact) the legal authority to act on their behalf. The principal signs it, and most states require notarization for the document to be valid for recording or use with financial institutions. Some states also require witnesses.
When you sign as someone’s attorney-in-fact, the signature line needs to communicate the legal relationship clearly. The standard format includes the principal’s name, your signature, and the phrase “as Attorney-in-Fact” or “as Agent”:
Jane Smith, by Alex Johnson, Attorney-in-Fact
Leaving off the “Attorney-in-Fact” designation is a mistake that can come back to haunt you. Without it, a third party might reasonably conclude that you were signing in your personal capacity, which could make you personally liable if something goes wrong. Always include the designation, even when it feels redundant.
Read the POA Before You Sign Anything
The scope of authority matters enormously. A general power of attorney gives the agent broad control over financial and legal matters, from managing bank accounts to selling property. A limited or special power of attorney restricts the agent to specific tasks, like signing closing documents for one real estate transaction. Before you sign anything as someone’s agent, read the power of attorney carefully to confirm the document you’re about to sign falls within your granted authority. Signing outside that scope makes you personally liable for the transaction and can void whatever you signed.
Also confirm the POA is still in force. A principal can revoke a POA at any time while mentally competent, and a POA automatically terminates when the principal dies. A durable power of attorney survives the principal’s incapacity; a non-durable POA terminates the moment the principal becomes unable to make decisions. If the document doesn’t explicitly say it’s durable, many states treat it as non-durable by default.
Proving Your Authority to Third Parties
Banks, title companies, and government agencies will almost always ask to see the power of attorney before accepting your signature. Bring a certified copy rather than the original, since some institutions keep the documents they receive. Many entities also require a certification or affidavit confirming that the POA hasn’t been revoked and remains in full force. Ask in advance what documentation the institution needs, because requirements vary and discovering a missing document at the closing table creates delays that help nobody.
Agents owe a fiduciary duty to the principal, which means acting in the principal’s best interest, avoiding conflicts of interest, and keeping records of every transaction. Roughly 30 states have adopted the Uniform Power of Attorney Act, which standardizes these duties and gives principals legal recourse if an agent mismanages their affairs. Breach of fiduciary duty can result in the agent being ordered to repay losses, return any profits from misuse of the principal’s assets, and cover the principal’s legal fees.
Signing in a Corporate Capacity
In a business setting, employees regularly sign letters and documents on behalf of executives or the company itself. The authorization here typically flows from the employment relationship and internal company policies rather than a power of attorney.
For routine correspondence, an assistant or deputy signs using the “for” format, placing their own name and then “for [Executive Name], [Title].” The signature block should sit above the typed name block to maintain a professional appearance and make clear the signer is acting in their employment capacity, not entering a personal obligation.
For contracts and other documents that legally bind the corporation, the stakes are higher. Companies typically authorize specific officers to sign through board resolutions. A board resolution identifies which officers or employees have authority to execute particular types of agreements on the company’s behalf. When a counterparty wants proof that someone can bind the company, the corporate secretary provides a certificate of incumbency or secretary’s certificate confirming the signer holds the relevant office and that the board authorized them to sign. Major transactions, lending agreements, and regulatory filings almost always require this documentation.
Electronic and Digital Signatures
Signing on someone’s behalf electronically is legally valid, but the same authorization requirements apply. A digital signature doesn’t bypass the need for a power of attorney or other written authorization when the document creates legal obligations.
The federal Electronic Signatures in Global and National Commerce Act (ESIGN) establishes that a signature or contract cannot be denied legal effect solely because it’s in electronic form. Most states have also adopted the Uniform Electronic Transactions Act, which provides a parallel framework at the state level. Together, these laws mean that an electronic proxy signature carries the same weight as a handwritten one, provided the standard requirements are met: the signer intended to sign, all parties consented to conducting business electronically, the signature is linked to the specific record, and the record can be retained and accurately reproduced.
When using platforms like DocuSign or Adobe Sign to execute documents as someone’s agent, upload or attach the power of attorney to the transaction so the receiving party can verify your authority. Most platforms allow you to add the “as Attorney-in-Fact” designation to the signature block. Keep a copy of the completed transaction record, including the audit trail showing when and how the signature was applied. That audit trail becomes important evidence if anyone later questions whether the signature was authorized.
A Note on Specialized Documents
A few categories fall outside the standard proxy-signature formats and have their own rules. A general power of attorney covering financial matters does not automatically grant authority over healthcare decisions; a healthcare power of attorney is a separate legal instrument in every state. Federal tax returns have their own regime under IRS Form 2848, and signing a return for another person is permitted only in narrow circumstances defined by Treasury Regulations. And for an incapacitated adult who never signed a POA while competent, the only path to signing authority is a court-appointed guardianship or conservatorship. If your situation falls into one of these buckets, the three formats above are not the complete answer.
Mistakes That Undermine a Proxy Signature
- Signing without identifying your capacity. If you just sign “Alex Johnson” on a contract that should bind Jane Smith, you may have personally obligated yourself. Always add the designation explaining your role.
- Using the wrong format for the context. The informal “for” notation works for office memos but won’t satisfy a title company or bank. Match the format to the document’s formality and legal significance.
- Failing to attach the POA. Telling someone you have a power of attorney isn’t the same as proving it. Bring certified copies to every transaction.
- Acting after revocation or death. A power of attorney dies with the principal. Any transaction you execute after the principal’s death is void, and you may be personally liable for the consequences.
- Exceeding your authority. A limited POA for banking doesn’t let you sell the principal’s house. Read the document before every new type of transaction, not just the first time.
The single best protection for anyone signing on behalf of someone else is documentation. Keep copies of the authorization, records of what you signed and when, and receipts for any financial transactions. If your authority is ever questioned, that paper trail is what separates an authorized agent from an unauthorized signer.