Son in military just joined how do i claim him

To claim him, he must satisfy the four tests below for Qualifying Child. If not there are further tests to see if he is a Qualifying Relative.

In general, to be a taxpayer’s qualifying child, a person must satisfy four tests:

• Relationship — the taxpayer’s child or stepchild (whether by blood or adoption), foster child, sibling or step-sibling, or a descendant of one of these.
• Residence — has the same principal residence as the taxpayer for more than half the tax year. Exceptions apply, in certain cases, for children of divorced or separated parents, kidnapped children, temporary absences, and for children who were born or died during the year.
• Age — must be under the age of 19 at the end of the tax year, or under the age of 24 if a full-time student for at least five months of the year, or be permanently and totally disabled at any time during the year.
• Support — did not provide more than one-half of his/her own support for the year.

If a child is claimed as a qualifying child by two or more taxpayers in a given year, the child will be the qualifying child of:

• the parent;
• if more than one taxpayer is the child’s parent, the one with whom the child lived for the longest time during the year, or, if the time was equal, the parent with the highest AGI;
• if no taxpayer is the child’s parent, the taxpayer with the highest adjusted gross income (AGI).

Qualifying Relative

• Do they live with you? Your relative must live at your residence all year or be on the list of “relatives who do not live with you” in Publication 501. About 30 types of relatives are on this list.
• Do they make less than $4,050? Your relative cannot have a gross income of more than $4,050 and be claimed by you as a dependent. 
• Do you financially support them? You must provide more than half of your relative’s total support each year.