For those N-400 Applicant who has a minor dependent below 18 yrs old → As per Child Citizenship Act (CCA) of 2000 children under 18 years of age as of Feb. 27, 2001 automatically acquire US Citizenship under former INA 320 and need NOT to file Form N-400 if they meet these following conditions:
- The child is a US Lawful Permanent Resident (“green card holder”)
- At least one parent must be a US Citizen by birth or naturalization.
- The child’s mother naturalizes if the child was born out of wedlock and paternity has not been established by legitimation.
- The child is residing in the United States pursuant to a lawful admission for permanent residence at the time the parent(s) naturalized or thereafter begins to reside permanently in the United States.
Therefore the minor children will immediately become a US Citizen upon their mother’s naturalization.

My 11 year son. He entered USA with a K2 Visa together with me.
To serve as evidence of being a US Citizen:
1. We will apply him a US blue passport after the Oath taking.
2. Or the Passport Officer will require him a US Citizenship Certificate (Form N600) before giving him a US passport, which also cost money . So let’s see how it goes.
Reference:
Chapter 4 – Acquisition of Citizenship Prior to Child Citizenship Act of 2000
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