What Is a Consent Letter and When Do You Need One?

A consent letter is a written document in which one person gives another person permission to do something specific, like travel with a child, obtain a passport for a minor, access medical records, or use copyrighted material. You need one any time a third party, government official, or border agent may reasonably ask whether permission was actually granted. The letter turns an informal yes into verifiable proof, and in several situations it is legally required before anyone will let you proceed.

When You Need a Consent Letter

The situations that call for one share a pattern: someone with authority over a person, a record, or a creative work is not present, and the party being asked to act wants written proof that the authority holder agreed. A few come up often enough to plan around.

International Travel With a Child

If a child crosses an international border with only one parent, a grandparent, or any adult who isn’t both legal guardians, many countries expect a signed letter from the absent parent saying the trip is authorized. The U.S. itself doesn’t require this letter when leaving the country, but border officials at the destination often do, and airlines sometimes check before boarding.

USAGov recommends the letter be in English and notarized, with a statement along these lines: “I acknowledge that my child is traveling outside the country with [name of the adult] with my permission.”¹ If both parents are staying behind and the child is traveling with someone else, both parents should sign. A parent who has sole custody should carry a copy of the custody order instead.

The State Department notes that some countries require a signed, notarized letter from the non-traveling parent, and others require proof of sole custody if you’re the only parent present.² Families who live near a land border and cross frequently should keep a current letter on hand at all times.

Some countries go further. Brazil requires a travel authorization for any Brazilian minor child leaving the country without both parents, even when the non-traveling parent is standing right there at check-in, and that authorization typically needs an apostille to be recognized.³ Always check the entry requirements for your destination before flying.

Passport Applications for Children Under 16

This is one of the most common situations in the U.S., and the one that catches people off guard. Federal regulations require both parents or legal guardians to appear in person and sign the application when applying for a passport for a child under 16.⁴ When one parent can’t show up, a consent form takes their place.

The absent parent must visit a notary public and sign Form DS-3053 (Statement of Consent), then provide a photocopy of the ID shown to the notary.⁵ These notarized statements expire three months after signing, so don’t get one notarized too far in advance. If you have sole legal custody, a certified copy of the court order replaces the consent form entirely.

Medical Treatment and Health Records

When a child needs medical care and the parent or guardian isn’t the one bringing them to the appointment, the treating provider will want written authorization from the parent. The same principle applies for adults who lack decision-making capacity, where a designated representative provides consent on their behalf. In genuine emergencies, doctors treat first and sort out paperwork afterward.

A related but distinct document is the HIPAA authorization, which grants permission for a healthcare provider to share your protected health information with a named third party. Federal regulations specify what a valid authorization must include: a description of the information being disclosed, who can disclose it, who receives it, the purpose, an expiration date, and the patient’s signature.⁶ The authorization must also tell you that you have the right to revoke it in writing.⁷

Employment Background Checks

Before an employer can run a background check on you, federal law requires written consent. Under the Fair Credit Reporting Act, the employer must give you a standalone written disclosure explaining that they intend to obtain a consumer report, and you must authorize it in writing before the report is pulled.⁸ The disclosure has to be a separate document, not buried in the fine print of a job application.

Using Someone Else’s Copyrighted Work

Federal copyright law gives the creator of an original work the exclusive right to reproduce, distribute, perform, and display it, and to authorize others to do any of those things.⁹ If you want to use someone’s photograph on your website, include a song in a video, or reprint an article in a newsletter, you need the rights holder’s written permission. In practice this often takes the form of a license agreement, but the function is identical: documenting that the rights holder said yes, specifying what uses are allowed, and setting the duration and scope.

What to Put in the Letter

Contents vary by purpose, but every effective letter answers the same questions: who is granting permission, who is receiving it, what exactly is being permitted, and for how long. Leaving any of these out creates the kind of ambiguity that makes the letter useless when it matters most.

Full legal names of both parties, matching government-issued IDs.
The subject of the consent. If it involves a child, include the child’s full name and date of birth. If it involves property or a specific action, describe it clearly enough that a stranger reading the letter would understand.
Scope and limitations. Spell out what is permitted and what isn’t. A travel letter might authorize a two-week trip to a specific country but not an open-ended stay.
Duration. State when the consent starts and when it expires. For passport consent, the government gives you a three-month window from the date of notarization.⁵
Date and signature. Without a signature, the document has no evidentiary weight.

For international travel, USAGov recommends writing the letter in English with a clear statement like: “I acknowledge that my child is traveling outside the country with [name of adult] with my permission.”¹ Some destination countries may want a translated version, so check requirements before departing.

Notarization and Apostilles

A consent letter doesn’t always need to be notarized, but notarization is strongly recommended for anything involving travel, passport applications, or legal proceedings. A notary public verifies your identity and watches you sign, which gives the document more credibility with officials and courts.

For passport applications, notarization isn’t optional. The State Department requires Form DS-3053 to be signed before a notary public, and a parent outside the United States may need to use a U.S. embassy or consulate.⁵ Electronically notarized documents are accepted if the state where the notarization occurred permits remote online notarization.

For international use, some countries require an apostille, which is a certification issued by a designated government authority confirming that the notary’s signature is legitimate. Brazil’s travel authorization is one example: the letter must be notarized and then apostilled before Brazilian border officials will accept it.³ Notary fees for a single signature typically range from a few dollars to around $15 depending on your state. Apostille fees and processing times vary more widely.

Taking Consent Back

Consent given in a letter can be revoked. How you revoke it depends on the context. For HIPAA authorizations, federal rules are specific: you must revoke in writing, and the revocation takes effect once the covered entity receives it.⁷ The original authorization itself must explain your right to revoke and describe the process.

Outside HIPAA, the formality required varies. As a practical matter, revoking in writing and delivering the revocation to the person who received the original letter creates the clearest record. If you granted permission in a notarized letter, a written revocation sent by certified mail leaves no room for someone to claim they didn’t know. Verbal revocation can work in some situations, but proving it happened is much harder if a dispute arises later.

How a Consent Letter Differs From a Power of Attorney

People sometimes confuse the two, and the difference matters. A consent letter gives someone permission to do one specific thing: take your child on a trip, access a particular medical record, use a photograph. A power of attorney grants someone broad legal authority to act on your behalf, such as signing contracts, managing bank accounts, or making healthcare decisions. The scope is fundamentally different, and so are the consequences of getting it wrong.

If all you need is to authorize a single action with clear boundaries, a consent letter is the right tool. If you need someone to step into your shoes and make ongoing decisions for you, that falls under power of attorney, and it usually requires more formal legal drafting.

1
USAGov. International Travel Documents for Children
2
U.S. Department of State – Bureau of Consular Affairs. Travel with Minors
3
Governo Federal. Travel Authorisation for Brazilian Minor Children
4
eCFR. 22 CFR 51.28 – Minors
5
U.S. Department of State. Apply for a Childs Passport Under 16
6
eCFR. 45 CFR 164.508 – Uses and Disclosures for Which an Authorization Is Required
7
U.S. Department of Health and Human Services. Can an Individual Revoke His or Her Authorization
8
Office of the Law Revision Counsel. 15 USC 1681b – Permissible Purposes of Consumer Reports
9
GovInfo. 17 USC 106 – Exclusive Rights in Copyrighted Works