If the policy excludes coverage for preexisting conditions for a limited time, that must be stated clearly on the first page of the policy. The waiting period for preexisting conditions may not be longer than 6 months, and only conditions treated during the 6 months before you take out the policy may be excluded. Insurers are required to waive any waiting periods for preexisting conditions if you buy a Medigap policy during the open enrollment period and have been continuously covered with creditable coverage for at least 6 months prior to applying for the Medigap policy. Insurers are also required to waive any waiting periods for preexisting conditions when one Medigap policy is replaced with another. For the first 6 months after people first enroll in Part B of Medicare, insurers must accept them regardless of their health.
Some companies have continuous open enrollments.
However, there may be waiting periods before coverage begins. An agent or company must give you an Outline of Coverage when selling you a new policy or converting one you already own. The Outline of Coverage is very important. It contains a chart summarizing the benefits provided by Medicare Parts A and B, and the benefits provided by the policy. The chart also shows which expenses are not covered by either.