NO, it's for my biological son.
my wife & son got k3/k4 after i got my citizenship and joined me in US and then they got GC and it's been 5years since they become permanent resident.
I'm doing N-400 for my wife, but not sure about my son's form ?
Thanks!
It is most likely that your son is already a U.S. citizen, under the CCA provisions.
(But you have to check that all the conditions of CCA are satisfied in his case: that he is a GC holder, under 18, and is residing in the U.S. in physical and legal custody of a U.S. citizen parent).
In that case the appropriate form to file for your son is N-600, application for a certificate of citizenship. Note, however, that N-600 approval does not result in
granting him U.S. citizenship - since he is a U.S. citizen already - but rather it merely results in USCIS issuing him a certificate confirming that he is a U.S. citizen.
N-600 filing in such cases is not mandatory, although it is recommended.
You can also apply for a U.S. passport for him directly, without filing N-600.
Still, it is a good idea for him to get a certificate of citizenship while he is still a minor. A certificate of citizenship is a non-expiring (unlike a U.S. passport) document confirming U.S. citizenship and it is easier to get it while he is still a minor, since it is less hassle to prove that the conditions of the CCA act are satisfied.