According to
publication 17, you are a full-time student if you are enrolled at a school for
the number of hours or classes that the school considers full time. You must be
full-time for some part of each of 5 calendar months during the year. This
means even if you were a full time student for just one day of the month, the
month counts. If you were a full time student (taking a full time
course load) for Jan - May, you would be considered a full time student for tax
purposes.