When you enroll in a Medigap policy – even during your Medigap open enrollment period – the insurance company does not have to cover pre-existing conditions for the first six months. However, you can shorten or eliminate this waiting period if you’ve had continuous creditable coverage prior to enrolling in the Medigap policy. (Continuous means you didn’t have a break of more than 63 days in the coverage.)
For each month that you had creditable coverage prior to enrolling in the Medigap plan, your pre-existing condition waiting period is shortened by a month. So if you had at least six months of continuous creditable coverage, your pre-existing condition waiting period would be eliminated and the policy would cover pre-existing conditions as soon as your plan takes effect.
If you didn’t have creditable coverage prior to your enrollment in Medigap, your Original Medicare will still cover pre-existing conditions. But your Medigap plan can deny claims related to the pre-existing conditions during your waiting period, which would mean you’d have to pay the Original Medicare out-of-pocket costs yourself until the waiting period was over.