In Aug, I adopted 2 children from China who became citizens upon entry into the US. For answering time lived with me question, do I say all year like a birth or 5 months?

[CherylW · Accepted solution]

An adopted child is always treated as your child, according to tax law.  This from IRS Publication 501, Exemptions, Standard Deduction, and Filing Information:

Adopted child. An adopted child is always treated as your own child. The term “adopted child” includes a child who was lawfully placed with you for legal adoption.

You may say they lived with you all year, regardless of when they arrived.

[two_stepin]

Does it matter if the child was born in 2016 and prior but adopted in 2017?

[CherylW]

No, just like it wouldn't matter if your birth child was born in July 2017.  She's considered having lived with you for the entire year.