Yes. By moving to a different county (or state), you will have to change medical groups and the Medicare Advantage plans available in that new county may be different/limited and/or have different copays and cost of drugs. Because you are not familiar with the doctors in your new area, you may want to consider going with a Medicare supplement plan so that you have freedom of choice to select your new doctors. If you decide to initially sign up with a Medicare supplement, you may, during the year, ensure that all of your doctors are in the same medical group and will take a Medicare Advantage plan so that you can switch to one of the local HMOs during the next Annual Enrollment.
Note: if you decide to go with a Medicare supplement, you will also need to sign up for a stand-alone drug plan. Unlike Medicare Advantage plans, Medicare supplements do not include drugs in their coverage – they only cover medical benefits.