Taxpayer, wife and son are all US citizens and all have valid "for work" SSN. Dad works here. Mom and son recently moved to Mexico for her healthcare reasons. Son is under 17. Dad visits in Mexico often. Dad is sole support of wife and son in Mexico and himself here. Since they are MFJ, and son lives in one of the two households with his Mom, can the MFJ return still claim the CTC on the son?