If you are not enrolled for any credits, including thesis or dissertation credits (e.g., during semesters you are in the field/lab conducting research), you must still register for the Continuation (Program) Fee only; otherwise, the Graduate School will automatically drop you from the program. Specifically, to register for Continuation Fee only, you must enroll (via SPIRE) in the following: GRADSCH 999 (note, the specific schedule # changes each semester, therefore check on SPIRE), and you will need to enroll before the last day of add/drop.
IMPORTANT: If you are paying continuation fee only (i.e., not enrolled for course credits, including thesis or dissertation credits) OR you are signed up for less than 5 credits (including thesis or dissertation credits), then you must physically go to the Health Center and sign up for Health Insurance at the beginning of each semester, otherwise it will be dropped automatically. Health Insurance is only automatically carried forward if you are signed up for 5 or more credits.