For most people, the best time to enroll in a Medicare supplement insurance (Medigap) plan is during their open enrollment period. 

Your Medigap open enrollment period starts the month in which you sign for for Medicare Part B. It lasts for six months. 

This is an ideal time to get a Medicare supplement because the insurance company is not allowed to deny you coverage for pre-existing conditions. 

But what if you change your mind later?  

Unhealthy seniors may have trouble getting a different Medicare supplement plan

You are allowed to change your Medigap plan at any time during the year, but the new insurance company doesn't have to approve your application. In most states, the company can deny you a plan if you have past health issues. This process is called medical underwriting. 

Their are exceptions. The states shown below have laws that let their residents switch plans with no medical underwriting. This is called a “guaranteed issue” right.

 • California and Oregon: Companies must let you join one of their plans every year during the first 30 days after your birthday. To be guaranteed enrollment, your new plan cannot be more generous than the one you're cancelling.

• Connecticut, New York and Washington: Insurance companies are required to let you change plans all year. You cannot be denied coverage because of your age or your health.

• Missouri: You can join a different Medigap plan once per year on the policy's anniversary date. If you bought a Humana plan on April 1, 2007, you may change plans on April 1 of any future year.

• Maine: This state has several rules about medical underwriting that make it relatively easy to change plans.

You can always cancel your policy

In every state, if you cancel your supplement policy to join a Medicare Advantage plan and you are not happy with that plan during the first 12 months, you have the right to return to your previous Medigap plan on a guaranteed issue basis. 

This is called the Medicare Advantage Trial Right but you can only use it once.

You are never required to keep your Medigap policy. If you wish to cancel your coverage, call the insurance company to let them know. Keep in mind that if you cancel your plan, you may not be able to get it back later.