Question: Ohio Subscriber Answer: Your physician can change his tax ID at any time, but you must submit a new W9 to your payers, in addition to a letter explaining that he will no longer be practicing under the group's tax ID. Downside: If your physician is currently part of a group, and he is leaving the group, he needs his own tax ID. Many legal issues will arise from this. For example, if he is staying in the same office suite, he will have to pay market rent for the offices and staff that he is using. When patients move between the old practice and his new practice, questions will arise about which patients are considered new and which are considered established patients. Much of this will have to be determined by the legal structure that is set up as he leaves the group. This can be a much more complex change than it appears on the surface. Your best bet is probably to consult a healthcare attorney.