I don't think there are any hard and fast rules about how to proceed. The entities who might have rules about it are your state medical board, your specialty board, the hospital where you might want to work in the future, the office where you might want to work in the future, or your present/future malpractice insurance carrier. In addition to rules, you will have to deal with people's attitudes about your hiatus.
In my situation, my state did not have an active practice requirement for maintaining licensure. You could check with your state. One hospital where I wanted to work had a requirement that one be in "active practice" within the previous 3 years. "Active practice" was not defined. Another hospital did not have that requirement at all and granted me privileges for procedures I had not done in many years.
There is also no roadmap for retraining/re-entry. I think it is good to work under supervision when re-entering, but I know of people who just jumped right in without supervision and did fine. Keeping up with your CME is important, but even if you do, you may be surprised by other changes in practice when you return. I know of one formal re-entry program in anesthesia, but I don't know about other specialties.
Professionally, it is soooooo much easier if you just work part-time. Probably even 1 day a week or maybe even less would be sufficient to maintain your "active" status. But if that is just not possible, then there is still hope.
