En español | You can’t be in more than one Part D at the same time. But that doesn’t mean that you’re forever locked into the first plan you choose. You have the opportunity to switch to a different plan once a year during open enrollment (Oct. 15 to Dec. 7) and at other times in certain circumstances.
If you switch to another Part D plan, your coverage in the old one is automatically canceled as soon as the new coverage becomes effective. Making a change during open enrollment means that the new coverage begins Jan. 1.