The major advantage of an HMO is the cost. HMO plans are some of the most cost affordable plan types. Copays, coinsurance, and monthly premiums are very low in HMO plans. However, these savings are at the expense of flexibility. In an HMO, your provider and hospital must be in-network. You must also find an in-network primary care physician (PCP) and, if you require a specialist, your PCP must give you a referral. Having a strict in-network vs. out-of-network system can save money in the short term, but it can also cost you a lot of money in the long run. If you need any care, like during travel or emergencies, outside of your network, you must pay extra.