A U.S. citizen or national can claim a legally adopted child who is not a U.S. citizen, U.S. resident alien, or U.S. national provided the child is a member of the taxpayers' household all year. All the other rules for a qualifying child or qualifying relative must be met. Of course, the children would have to obtain SSNs, ITINs, or ATINs to be claimed on the taxpayers' tax return.
An Adoption Taxpayer Identification Number (ATIN) can be obtained when a domestic adoption is pending and other rules are met. An ATIN can be obtained in the case of a foreign adoption when the child already possesses a green card or a certificate of citizenship, which is a form claiming citizenship because a child was born overseas to a U.S. citizen.
See Publication 17, Chapter 3, Personal Exemptions and Dependents, for more information about the citizen or resident test, including who is considered a U.S. national.
An adopted nonresident alien child must live with the taxpayer all year to pass the citizen or resident test.