The child does not have to be a 'Qualifying child' to be claimed as a dependent, it is one of the two ways a child could be claimed. The other is as a "Qualifying relative," which applies if the child does not meet all the 'Qualifying child' criteria. Stripped down for your situation, the 'Qualifying relative' tests do not have an age limit, and they are -
- doesn't meet all the 'Qualifying child' tests
- you provide more than half the relative's support
- the relative must be within a specified set of relatives (Which includes a child or stepchild who isn't a 'Qualifying child') and does NOT have to live with you
- the child cannot have earned over a specified amount (Usually different from year to year, it was $3700 in tax year 2011). This is the one likely to be a problem for you.
So, if your child isn't working or at least not making anything much, and you're providing over half the support, he should be a 'Qualifying relative' if he fails to meet the criteria for 'Qualifying child."
Important to note, 'Qualifying child' for purposes of claiming a dependent exemption may be, but isn't necessarily, the same thing the phrase 'Qualifying child' might mean for other credit or deduction purposes, like education expenses. Unless the instructions make it clear that they really are talking about the same thing as in the dependency exemption, there may be additional or different hoops involved in 'Qualifying' for whatever the thing at hand might be at that point in the forms and schedules.