If I am on disability with a supplemental insurance plan, do I need to change at age 65 to a Medicare supplemental plan?

If you r on Social Security Disb. u should already be on Medicare or at least Medicaid. My nephew is on NJ Horizon as supplimental and (Medicaid) Medicare as primary.

States usually anticipate you wanting to explore and maybe change coverage when you 'age in' to Medicare. You can stay on the supplement you have or change to another plan available at 65 that best fits your needs. Several months prior you will have lots of agents waiting to help you. Contacting Medicare will also help educate you.