Medigap is supplemental insurance sold by private companies that can be used along with Medicare Parts A & B.  

Medicare covers many healthcare costs, but it does not pay for every expense. These additional costs are sometimes called the “gaps” in Medicare coverage. Medigap helps pay for the gaps, similar to retiree insurance. Medigap plans may pay for copayments, coinsurance and deductible costs. For those with a Medigap policy, Medicare pays their share first and then the Medigap plan pays their share of costs.  

Some of the out-of-pocket costs you may incur in 2021 are in the graphic below.