My son graduated high school in may. Turned 19 in June. Was enrolled full time in college in august but left in september returned home Can I claim him.

Yes, you can claim your Son as a dependent since he was under the age of 24 and lived with you for more than half the year, as long as he meets the definition of a student, and you meet all of the other requirements. Please refer to page 13 of Pub 501 under the headings, "age test", "student defined", "full time student", "school defined", and "vocational high school students" to determine if he meets the definition of a student. https://www.irs.gov/pub/irs-pdf/p501.pdf

If he does NOT meet the definition of a student, you can still claim him as long as you provided more than half of his total support and his gross income for 2016 is less than $4050. Please refer to the chart on page 12 of pub 501 to see if you meet the requirements to claim your child as a dependent. https://www.irs.gov/pub/irs-pdf/p501.pdf.