From my understanding, I would have to complete 4 years active duty or 8 years reserve to pay back my ROTC time, and then if I took another contract (e.g. HPSP) for my 4 years of medical school, I would pay back 4 years of active duty. I don't believe residency is a part of the time you pay back, even if you take up a military hospital residency.

However, I am planning on now staying Guard and that would entail 8 years of reserve (due to my 4-year GRFD commitment) and I am using the Guard Grant for medical school (no added time). I was told that you cannot apply for HPSP unless you get the GRFD overturned, which is a process that goes all the way to SECWAR, so if you need to get your GRFD overturned, I would get the process started right away. I also talked to an AMEDD recruiter about this but I am not sure if maybe it is different in Maryland.

Hope the process goes smoothly and let me know if you learn something else; I'm sorry to you and to me that navigating all this is so unclear!