IRS Pub 969 defines a full-time student as follows:
Full-time student. You are a full-time student if, during some part of each of 5 calendar months (not necessarily consecutive) during the calendar year, you are either:
- A full-time student at a school that has a regular teaching staff, course of study, and regularly enrolled body of students in attendance; or
- A student taking a full-time, on-farm training course given by either a school that has a regular teaching staff, course of study, and regularly enrolled body of students in attendance, or a state, county, or local government.
You are a full-time student if you are enrolled for the number of hours or courses the school considers to be full time.
In your case, it appears that you were a full-time student in only 4 months of 2018, so you are not considered a full-time student for 2018 for the purpose of an HSA contribution.
