The set time each year (Oct. 15 to Dec. 7) when you can change your Medicare coverage choices. Sometimes called fall open enrollment.

The action you can take if you don’t agree with a decision made by Medicare or your Medicare Advantage plan about your coverage. You might appeal decisions such as a change in the amount you have to pay for a drug or service or the availability of a drug or service. This is also sometimes called a redetermination.

When there is a difference between your provider’s charge and the amount covered by Medicare, your provider might bill you for that difference. Medicare-preferred providers are not allowed to balance bill you. Most physicians and hospitals are participating providers in Medicare so they cannot balance bill you.

The request you submit to Medicare for payment when you see a doctor or receive medical care or supplies that are covered by your plan.

This is the seven-month period when you’re eligible to sign up for Medicare for the first time. It starts 3 months before you turn 65 and ends 3 months after the month you turn 65. If you miss this window, you may have to wait to sign up and pay a monthly late enrollment penalty. An exception to the penalty is if you or your spouse continues to work and you have insurance through your employer.

Private companies that contract with Medicare offer this plan, which is also called Part C. Medicare Advantage takes the place of Original Medicare and includes all Medicare benefits, plus usually adds coverage for things like dental care, vision services, or medications. Some Medicare Advantage plans include prescription drugs. Medicare Advantage plans require you to see providers in their network, in most cases, and may require you to get prior authorization for some services.

A medical professional who isn’t under contract with your Medicare Advantage plan to provide services to you. You pay more to see a non-preferred provider.

Original Medicare is a plan that combines two Medicare parts: Part A (hospital insurance) and Part B (medical insurance). This plan does not include prescription coverage, which is part of Plan D (Medicare drug plan) and is purchased separately.

A penalty is a fee added to your monthly premium (bill) for Part B or a Medicare drug plan (Part D). You get this penalty if you don't join Medicare or enroll in a Part D plan when you're first eligible, and you pay it as long as you have Medicare. If you or your spouse has health insurance through an employer, you may not be subject to the penalty for late enrollment.

A time period during which you’re allowed to make changes to your Medicare Advantage and Medicare prescription drug coverage after certain events happen in your life, like a move or loss of other health insurance.