You may only claim his college expenses if you are claiming him as a dependent. The $4050+ may or may not prevent you from claiming him as a dependent.
There
are two types of dependents, "Qualifying Children"(QC) and standard ("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, a relationship test and a residence test.
A child of a taxpayer can still be a “Qualifying Child” (QC) dependent, regardless of his/her income, if:
1. He is under age 19, or under 24
if a full time student for at least 5 months of the year, or is totally &
permanently disabled
2. He did not provide more than 1/2 his own support. Scholarships are
considered third party support and not as support provided by the student.
3. He lived with the parent
(including temporary absences such as away at school) for more than half
the year
