If you follow your Health Maintenance Organization’s (HMOs) rules and you do not need a lot of health care services, you may save money by being in an HMO. This is because you generally pay only a small copayment for most services and premiums may be lower than having Original Medicare and a Medigap plan. All HMOs must have a limit on your out-of-pocket costs (deductibles and co-pays). These limits, called maximum out-of-pocket costs, can be high but they may protect you from excessive costs if you need a lot of care or expensive treatment. The maximum out-of-pocket cost for most HMOs in 2018 is $6,700. 

You may also get extra benefits in an HMO that Original Medicare does not cover, such as dental and vision care.