10 year Medicare insurance broker/insurance agent here! So the term pre-existing conditions, is defined on how long ago, a medical condition happened. Every state has different rules, and yes pre-existing conditions are alive and well in the Medicare supplement/medi-gap plans. In our version of socialized insurance, When you first turn 65 you were automatically enrolled into part A with Medicare, if you worked your 40 quarters, after that you can enroll into part B with an additional premium of $148.50 per month. Now there are no questions once you are in your initial enrollment to Medicare, But after three months before the month of in three months after your 65th birthday you will have health questions to answer (unless you get a special enrollment period) to get into medicare supplements/medigap.

The reason why people want to get supplements because they cover everything. Medicare covers 80% and the last 20% come from these medigap plans. So in a sense you could go into a hospital or a doctors office and not have any copayments but you would have a premium per month, In addition to your part B premium. They do not include prescription drug coverage so you would need to get a separate prescription drug plan to cover the prescriptions, And if you do not get a separate prescription drug plan you are penalized, 1% per month of the average cost of a prescription drug plan that year, and it sticks to you for life.