Medicare HMO plans are a type of coordinated care in which you will choose a primary care doctor in the network. You usually must get a referral from that doctor before you can see a network specialist.

Medicare HMO plans often have the lowest monthly premiums of the three types of Medicare Advantage programs. This is because they are generally the most restrictive, requiring a primary care physician. Members visit their PCP first to obtain a referral before they can see a specialist.

Medicare PPO plans are also coordinated care plans but are largely more flexible than Medicare HMO plans. Members can usually see any doctor in the network without a referral. You can also receive treatment outside the network, although you will spend more to do so.

Medicare PFFS (Private-Fee-for-Service) plans largely have no network or a very small network. You can see any doctor who will bill the plan as long as they agree to the plan’s terms and conditions upfront. This puts the burden on you to ask your providers whether they will accept the plan before you seek medical services. These plans have been phased out in many counties where at least 2 other plan types exist.

Always check the rules of your specific plan, which can be found in the plan’s Summary of Benefits.