Medicare, explained in large print.

The plain-English glossary.

Stuck on a word? Type it below, or open any term. Every answer is short and written for people, not for insurers.

• Annual Election Period

  The yearly window, October 15 to December 7, when you can generally join, switch or drop a Medicare Advantage plan or a Part D drug plan. Changes usually start January 1.

  Also called the Fall open enrollment.

• Coinsurance

  A percentage of a service's cost that you pay after any deductible. If your coinsurance is 20 percent, the plan pays the rest of the approved amount.

  A share of the bill.

• Copayment (copay)

  A fixed amount you pay for a covered service, such as a doctor visit or a prescription, at the time you receive it.

  A flat fee.

• Cost sharing

  The part of a medical bill that you pay yourself instead of the plan. It can take the form of a deductible, a copayment or coinsurance.

  See also: deductible, copayment, coinsurance.

• Creditable coverage

  Drug coverage from another source, such as an employer, that is expected to pay at least as much as standard Medicare drug coverage. Having it can affect whether a late-enrollment penalty applies.

  Mostly about drug plans.

• Deductible

  The amount you pay for covered care each period before your plan starts to pay its share.

  What you pay first.

• Extra Help

  A federal program that helps some people with limited income and resources pay for Medicare drug coverage. Social Security decides who qualifies.

  Also called the Low-Income Subsidy.

• Formulary

  The list of prescription drugs a Part D or Medicare Advantage plan covers. Lists can change, and drugs may be placed in different cost tiers.

  A plan's drug list.

• General Enrollment Period

  A yearly window for people who did not sign up for Part A or Part B when first eligible and who do not qualify for a Special Enrollment Period. Coverage generally starts the month after sign-up.

  January 1 to March 31.

• HMO plan

  A Health Maintenance Organization plan generally covers care from doctors and hospitals in its network. You may need a referral to see a specialist.

  A kind of Medicare Advantage plan.

• Initial Enrollment Period

  A 7-month window around your 65th birthday: the three months before your birthday month, the month itself, and the three months after. It is when many people first sign up for Part A and Part B.

  Your first window.

• Late-enrollment penalty

  An extra amount that can be added to what you pay if you did not sign up for certain parts of Medicare, or drug coverage, when first able and had no qualifying coverage. Rules differ by part.

  An added cost for waiting.

• Medicaid

  A joint federal and state program that helps some people with limited income and resources pay for health care. It is separate from Medicare, and some people have both.

  A different program.

• Medicare Advantage (Part C)

  A way to get Medicare Part A and Part B benefits through a private company approved by Medicare. Plans often include drug coverage and may offer extras, and they usually use a network of providers.

  A private-plan option.

• Medicare Number

  The unique number assigned to you when you enroll. Keep it private, and share it only with people and offices you trust.

  Your Medicare identifier.

• Medigap (Medicare Supplement)

  Insurance that helps pay some costs Original Medicare does not, such as certain copayments and deductibles. It works with Original Medicare and not with Medicare Advantage. Rules vary by state.

  Sold by private insurers.

• Network

  The doctors, hospitals and other providers that a plan has agreed to work with. Using providers outside the network can cost more or may not be covered.

  The doctors a plan uses.

• Original Medicare

  The federal program made up of Part A (hospital insurance) and Part B (medical insurance). You can usually see any doctor or hospital that accepts Medicare.

  Parts A and B.

• Out-of-pocket maximum

  A limit on what you pay in a year for covered services in certain plans, such as Medicare Advantage. After you reach it, the plan covers the covered costs for the rest of the year.

  A yearly ceiling in some plans.

• Part A

  Helps cover inpatient hospital stays, limited skilled nursing facility care, hospice and some home health care.

  Hospital insurance.

• Part B

  Helps cover doctor visits, outpatient care, many preventive services and some medical supplies and equipment.

  Medical insurance.

• Part D

  Helps cover the cost of prescription drugs. It is offered by private companies, either as a stand-alone plan or built into some Medicare Advantage plans.

  Prescription drug coverage.

• PPO plan

  A Preferred Provider Organization plan has a network but usually lets you see out-of-network providers too, often at a higher cost.

  A kind of Medicare Advantage plan.

• Premium

  The amount you pay, usually monthly, to have a plan or coverage, whether or not you use any care.

  The regular payment.

• Prior authorization

  A requirement that your plan approve a service, test or drug before you get it, in order for it to be covered.

  Approval before care.

• Provider

  A doctor, hospital, clinic, pharmacy, therapist or other person or place that provides health care.

  Anyone who gives care.

• SHIP

  A free, federally funded counseling program in every state where trained volunteers and staff answer Medicare questions without selling anything.

  State Health Insurance Assistance Program.

• Special Enrollment Period

  A limited window outside the usual dates that may open after events such as moving out of your plan's area or losing employer coverage. Length and rules depend on the event.

  After a life event.

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