Click the link below for Passport Forms to apply for a Passport 

https://travel.state.gov/content/travel/en/passports/apply-renew-passport/under-16.html
8 Steps for a Childs Passport_SPANISH Handout

The most common form is: 

DS-3053 – Passport Form, “Statement of Consent: Issuance of a U.S. Passport to a Minor Under Age 16”

3053

Passport Form DS-5525 is a Statement of Exigent/Special Family Circumstances for Issuance of a U.S. Passport to a Minor Under Age 16
Most people can use form DS-5525, if you have had difficulty getting the non-applying parent to give consent for your minor child under 16 years old to obtain a passport book or card.

Attach a statement detailing the reason why the other parent can’t/won’t sign the consent form (DS-3053).
Attach any evidence regarding your circumstances.
Explain methods you have used to try to obtain consent.

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