A collapsed lung, also known as a pneumothorax, occurs when air escapes out of a lung and becomes trapped inside the space between the chest and lung cavities. This can be caused by air blisters in the lungs that break open, sudden air pressure changes, or trauma to the chest or ribcage.
The IRS interpreted this provision as applying only to full-time students. In a 1993 technical advice memorandum, the IRS provided a safe-harbor definition of a full-time undergraduate student as one who is taking 12 credit hours and working no more than 20 hours per week.
If he was a full time student (high school or college) during some part of 5 months in 2013, he qualifies as a full time student and can be claimed as your dependent (assuming he meets the other dependency tests) even though he is 18. Hereâs the IRSâs definition of a full time student: