Understanding the ins and outs of Medicare coverage can be challenging for many people. There are four parts to Medicare — Parts A, B, C, and D. Part C Medicare coverage is often referred to as a Medicare Advantage plan.

Medicare Advantage plans were implemented by the government to provide people with an alternative to Original Medicare coverage (which includes Part A and B). Here are some things that you need to remember about Medicare Advantage coverage so that you can make an informed decision when enrolling in a Medicare program in the future.

1. You Must Work With a Private Insurance Company

Medicare Advantage plans are sold by private insurance companies. This means that the coverage included in the policy can vary from one insurer to the next. It's important that you take the time to shop around if you are considered Medicare Advantage coverage.

Find several insurance agencies that specialize in Medicare plans, then compare policies to identify which agency can offer you the Medicare Advantage plan that will best suit your lifestyle.

2. Medicare Advantage Is an Add-On Plan

Medicare Advantage policies help supplement the coverage offered by Medicare Parts A and B. In order to sign up for a Medicare Advantage plan, you must have an active Part A and Part B policy in place. These Original Medicare policies can only be obtained through the Federal Government.

You are eligible to enroll in Medicare Parts A and B starting three months before your 65th birthday. The enrollment period ends three months after your 65th birthday. If you miss this enrollment window, you will have to wait until the next general enrollment period to secure your Medicare coverage. Be sure that you are fully enrolled in Medicare Parts A and B before you attempt to purchase a Medicare Advantage plan through a private insurance agency.

3. You Will Have Out-of-Pocket Costs

Medicare Advantage plans help subsidize the cost of healthcare, but they do not offer complete coverage for medical services. You will still have to pay some costs out of your own pocket.

The government sets a maximum out-of-pocket limit for Medicare Advantage plans each year. Each individual insurance agency can then determine the out-of-pocket costs that are required for the Medicare Advantage plans they offer their customers. As long as the out-of-pocket requirement doesn't exceed the government-mandated maximum, an insurance agency is able to adjust its out-of-pocket limits to reflect the market in which their policies provide coverage.

Look for a company like Insurance for Seniors & Disabled that can tell you more about Medicare Advantage plans (Part C).