
Starting in the first month that you are covered under Medicare Part B and you are age 65 or older, there is a one-time-only six-month period in which you can buy any Medigap policy available in your state.
During this period, you can’t be denied coverage or charged more due to past or present health problems.
The insurance company can’t make you wait for your coverage to start. But, it may be able to make you wait for coverage of a “pre-existing condition” (a health problem you have before the date a new insurance policy starts). In some cases, the Medigap insurance company can refuse to cover your out-of-pocket costs associated with pre-existing condition problems for up to 6 months (Medigap waiting period) if the condition was treated or diagnosed within 6 months before the date the Medigap coverage starts. After this 6-month period, Medigap will cover the condition that was excluded.
Medicare coverage is unaffected by the Medigap waiting period.

