Sorry, you are not eligible to claim your son as a dependent. He made more than $4050 during 2016- it doesn't matter when. A tax year is not prorated.
The year is looked at as a whole, and never by periods or months. Because he was not under 24, he does not fit into the Qualifying Child category. To be a Qualifying Relative, you must pass all 4 of these tests for 2016:
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Not a qualifying child test,
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Member of household or relationship test,
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Gross income test, and DOES NOT PASS due to income over $4,050
- Support test
https://www.irs.gov/uac/who-can-i-claim-as-a-dependent
You can use the tool above to get the feedback from the IRS.
