Yes. Although you are already on Medicare insurance, when you are turning 65 you receive a new election period and can make a change in your coverage.
If, when you initially became eligible for Medicare coverage, you:
* joined a Medicare Advantage/HMO plan and now you want to change your Medicare Advantage carrier or change to a medigap/Medicare Supplement and stand alone drug plan, you can as a guaranteed issue.
* joined a medigap/Medicare Supplement and want to change insurance carriers and/or your stand alone drug plan /or/ change to a Medicare Advantage/HMO plan, you can as a guaranteed issue.
Please remember, however, that wherever you are regarding prescription drug coverage (i.e., are you still in the initial discount stage or are you in the donut hole?), will carry with you should you change drug plan providers.