To qualify, a child must have been under age 17 (i.e., 16 years old or younger) at the end of the tax year for which you claim the credit. The child must be your own child, a stepchild, or a foster child placed with you by a court or authorized agency.
https://turbotax.intuit.com/tax-tips/family/7-requirements-for-the-child-tax-credit/L3wpfbpwQ
Disclaimer: Not a tax professional. Information gathered from internet links. Anything dated in June 2019 was posted in prior years and is before the 2019 limits and changes.
