An applicant has to be a US citizen to become eligible for filing N-600 form (Application for Certificate of Citizenship). The applicant is considered eligible only if he/she has become a citizen of U.S. through law or he/she was born outside the US to parent(s) who are U.S. citizens.
According to the Child Citizenship Act of 2000, some foreign-born adopted or biological children of U.S. citizens are permitted to obtain U.S. citizenship automatically. These children acquired the U.S. citizenship, not at birth but later when they entered the U.S. as lawful permanent residents.
In the case of the biological child, the parent must be a U.S. citizen. The parent can either be a citizen by birth or could have gained citizenship through the naturalization process. The child must be below 18 years. Also, the child must live in the physical and legal custody of the parent who is a U.S. citizen. The child should have been admitted into the country as a lawful permanent resident.
An adopted child should have been admitted to the U.S. for permanent residence. A child adopted abroad enters on an IR-3 visa whereas if the child is being brought to the U.S. to be adopted in the U.S., then he/she enters on an IR-4 visa. In this case, the adoption should be complete and final in the United States, only then the applicant can file for the certificate of U.S. citizenship.
Adopted children below the age of 18, and claiming citizenship under Section 320 of the INA should have the applications filed by their U.S. citizen parent or legal guardian who has their legal custody.
The N-600 form can also be filed by those who are 18 years or older. This is possible only if the applicant met all the qualifying criteria before he/she became 18 years of age, and he/she should have been below 18 on Feb 27, 2001. In this case, the applicant can file the application by himself/herself. Unsigned applications are returned to the United States Citizenship and Immigration Services (USCIS).
Access Form N-600 to apply for US citizenship.
After filing, the N-600 form is checked by the USCIS for its completeness and required documents. The USCIS can either request for more information, if required or can ask the applicant to appear for an interview after reviewing the N-600 form. After taking all the factors into consideration, a decision regarding your application will be taken by the USCIS.