Maybe. There are two types of dependents, "Qualifying Children"(QC) and
other ("Qualifying Relative" in IRS parlance even though they don't
have to actually be related). There is no income limit for a QC but there is an
age limit and residency requirement. Only a QC qualifies you for the Earned Income Credit and Child Tax Credit.
They cannot be your QC unless you had physical custody prior to to the legal custody in August. They must have lived with you for more than half the year.
Another requirement to claim a dependent, is that they not be the QC of another taxpayer. So, if they also did not live with either of their parents, or foster parents, for more than half the year, they are probably not the QC of anybody for 2015.
So that leads us to the question, can they be your Qualifying Relative (QR) dependent. A person can still be a Qualifying relative dependent, if he meets the 6
tests for claiming a dependent:
1. Closely Related (nieces, nephews and foster children are) OR live
with you ALL year
2. His/her gross taxable income for the year must be less than $4,000 (2015)
3. You must have provided
more than 1/2 his support for the year
In either case:
4. He must be a US citizen or resident of the US, Canada
or Mexico
5. He must not file a joint
return with his spouse or be claiming a dependent of his own
6. He must not be the
qualifying child of another taxpayer
He must have a US social
security number or tax identification number (TIN)
