Supplemental insurance or coverage is a policy purchased by a beneficiary to help pay for expenses not paid by Medicare, such as deductibles, coinsurance, and excluded services. 
Supplemental insurers may arrange for Medicare to file supplemental claims automatically. In cases where supplemental insurers do not have this arrangement with Medicare, beneficiaries must file their own supplemental claims. Traditional supplemental insurance policies directly reimburse patients who are in turn responsible for reimbursing the healthcare provider. Exclusions include: 
* Date(s) of service outside the patient ’ s eligibility period 
*Claims paid at 100 percent of Medicare approved amount 
*Medicare claims containing totally denied services
Medigap is privately offered Medicare supplemental health insurance specifically designed to supplement Medicare benefits. 
A Medigap plan is a health insurance plan that helps bridge gaps in Medicare plan coverage. In all states, there are basic standardized Medigap plans. Each plan has a different set of benefits and provides payment for some expenses not paid by Medicare such as deductibles, coinsurance, or other limitations imposed by Medicare.