[header] How to get the child tax credit [title] Meet the age and relationship tests. [step] You may be able to claim the child tax credit for each child under the age of 17 who is your son, daughter, stepchild, foster child, sibling, step-sibling, or a descendant of any of those people. [substeps] Descendants include your nieces or nephews as well as your grandchildren. 
For purposes of the child tax credit, adopted children are considered your own children. This includes any child placed with you for adoption regardless of whether the legal process of adoption is finished by the end of the year.