The cost of a specific insurance policy for a given period of time. You typically pay this monthly, quarterly, or annually. 

For example, if your annual premium is $1,200, your plan costs $120/month. 

The amount of money you’re required to pay for services after your deductible has been paid.

For example, if your co-insurance is 15 percent, you’ll pay 15 percent of the cost of your medical bills.

A fixed amount you pay at the time of service. You typically pay this after your deductible has been met.  

Not all plans have co-pays, and some services like annual checkups and preventative care may not require a co-pay. 

The actual charges incurred for medical services and supplies that are medically necessary.

The amount you must pay out of pocket for your medical care before the insurance company will pay for any expenses.  

For example, if your deductible is $500, your insurance plan won’t pay for any health care expenses until you’ve paid $500 out of pocket. Co-pays (typically) and premiums don’t count toward your deductible. 

An Exclusive Provider Organization (EPO) is an insurance plan that provides care through a specific, often local, network of providers, clinics, and hospitals; out-of-network care is not covered (except in emergencies). You don't have to select a primary care provider or get a referral to see a specialist. 

An EOB is not a bill—it is a document that lets you know your insurance company has processed a claim on your behalf, what it was for, whether it was approved, and for how much. Always check your EOB to make sure it’s correct, and contact your insurance company with questions. 

A Health Maintenance Organization (HMO) is a health insurance plan that provides care through a specific network of providers, clinics, and hospitals; out-of-network care is generally not covered (except in emergencies). You must select a primary care provider and get referrals to see specialists. An HMO may require you to live or work in its service area to be eligible for coverage. 

You’ll often hear of clinics or providers being “in network” or “out of network.” The network is the facilities and providers your insurer has contracted with to provide services. Services with in-network providers and clinics are covered by your insurance and may reduce your out-of-pocket expenses; services with out-of-network providers may not be covered. 

A provider who is not part of your health insurer’s network of providers. Depending on your insurer, costs can be significantly higher to see a provider who is out of network (or your insurer may not cover out-of-network expenses at all). 

A decision by your insurer that a service, medication, or procedure is medically necessary. Your insurer may require preauthorization (also called prior authorization) for certain health care services before you receive them (except in emergencies).  

A health care provider who is part of your health insurer’s network. It generally costs you less to see a preferred provider. 

A Preferred Provider Organization (PPO) is a health insurance plan that provides care through a specific network of providers, clinics, and hospitals; you can see out-of-network providers at an additional cost. You don’t select a primary care provider, and no referrals are necessary to see specialists.  

A referral is a recommendation or order from your primary care provider for you to see a specialist. With many types of insurance, you must get a referral before seeing a specialist; if you don’t, your insurance may not pay for the services you receive from the specialist.