That would depend on why he failed to qualify as a dependent on your federal tax return.
Briefly, the federal rules for claiming dependents fall into two categories:
- They are related to you;
- They aren't claimed as a dependent by someone else;
- They are a U.S. citizen, resident alien, U.S. national, or a Canadian or Mexican resident.
- They aren’t filing a joint return with their spouse or are filing a joint return only to claim a refund of withheld income tax or estimated tax paid;
- They are under the age of 19, or 24 if a full-time student;
- No age limit for permanently and totally disabled children.
- They live with you for more than half the year (temporary absences from your home, while living at school, still count as time living with you); and
- They didn't provide more than half of their own support for the year.
A new requirement this year is that each qualifying child dependent must have a Social Security Number, issued before the due date of your tax return (including extensions) to be claimed for the Child Tax Credit.
- They don't have to be related to you (despite the name).
- They aren't claimed as a dependent by someone else.
- They are a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
- They aren’t filing a joint return with their spouse.
- They are related to you or lived with you the entire year as a member of your household.
- They made less than $4,150 in 2018.
- You provided more than half of their financial support.