I’m a U.S. citizen living in Ireland, and married to an Irish citizen. She has a son from a previous marriage. He was 16 years old when his mother and I married. Now he’s 18, and his dream is to go to the U.S. and make it in the music world. Can I sponsor him for a U.S. green card? By the way, he’s not married.
It may be possible for you to petition for your stepson to get U.S. lawful permanent residence (a green card), but it won’t be straightforward.
Let’s start with the easier part of the process. Given that you are a U.S. citizen, married to the child’s mother, and that the marriage took place before he turned 18, and that he remains under age 21 and unmarried, it appears that he fits the immigration law definition of your “immediate relative.”
Noncitizens who are immediate relatives of U.S. citizens are eligible for lawful permanent residence in unlimited numbers, meaning there is no wait for a visa to become available (as occurs with some other categories of relatives). (See Green Card Through a U.S. Family Member: Who Qualifies? for details.)
To start the process, you would prepare and submit Form I-130 to the appropriate U.S. government agency. Your stepson would need to then prepare additional forms and documents, and eventually attend an interview at a U.S. embassy or consulate in Ireland.
Here is where things get sticky, however. Like every intending immigrant, your stepson will need to prove that he is not “inadmissible” to the United States. U.S. immigration law contains numerous grounds of inadmissibility, barring noncitizens from entry for security, criminal, health, financial, and other reasons. Even presuming your stepson has a clean record in every other way, he is expected to prove that he will not likely become a “public charge” (dependent on need-based government assistance) by having you, as the petitioner, sign paperwork promising to act as his financial sponsor in the United States. The paperwork in question is a Form I-864 Affidavit of Support.
But if you are not moving to the U.S. with him--and therefore will not be “domiciled” in the U.S.--you are not eligible to serve as your stepson’s sole sponsor. You will still have to fill out a Form I-864, but you will most likely need to find someone within the U.S. to serve as a joint sponsor. This is no small thing to ask of someone, as described in What Sponsors Should Know Before Signing Form I-864 Affidavit of Support.
Your best bet at this point is to consult with an experienced U.S. immigration attorney, preferably in the state where your stepson intends to live or where a likely joint sponsor resides.
A final note: If at some point you and your wife decide to live in the U.S. and you sponsor her for a green card, you will run into this same issue – but it will be much easier to overcome, when you provide evidence that you will very soon be domiciled in the United States.