Medicare Supplement Plan N, introduced in 2010, offers lower monthly premiums in exchange for you paying the Part B deductible, certain co-pays for doctor and emergency room visits, and any excess charges (up to 15% above what Medicare approves). Plan N covers the 20% that Medicare Part B doesn’t pay, along with your hospital deductible and all hospital co-pays and coinsurance. Routine preventive care continues to be fully covered by Medicare.