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.
Tax Year. DEFINITION of 'Tax Year'. The period of time which is covered by a particular tax return. Many firms simply use the calendar year as their tax year, however this is not always required. When a firm begins or ends operations, it often needs to file a tax return for a shorter time period than a full 12 months.