I started graduate school in September. Does that mean I am not a full time student for 2021?

[HelenC12]

According to the IRS, a full-time student is defined as a student who is enrolled for the number of hours or courses that the school considers to be full-time attendance. Keep in mind that each school defines "full time" in its own way (usually in terms of the number of courses or hours).

To qualify as a student, the person must be (during some part of each of any five calendar months of the year):

1. A full-time student at a school that has a regular teaching staff, course of study, and a regularly enrolled student body at the school, or
2. A student taking a full-time, on-farm training course given by a school described in (1), or by a state, county, or local government agency.

Note: The five calendar months do not have to be consecutive. 

[Bsch4477]

If you were a full time student as determined by your school any part of 5 months then you were a full time student.