Your monthly Medicare Part D premium can be broken into two parts: the Basic and Supplemental Premiums.  And Medicare provides the technical definitions of Total Premium, Basic Premium, and Supplemental Premium:

“Part D Total Premium: The Part D Total Premium is the sum of the Basic and Supplemental Premiums.  Note the Part D Total Premium is net of any Part A/B rebates applied to "buy down" the drug premium for Medicare Advantage plans; for some plans the total premium may be lower than the sum of the basic and supplemental premiums due to negative basic or supplemental premiums.

Part D Basic Premium:  The Part D Basic Premium covers the basic prescription benefit only and does not cover enhanced drug benefits, medical benefits, or hospital benefits.  Note: the Part D Basic Premium is net of any Part A/B rebates applied to "buy down" the drug premium for Medicare Advantage plans.  Beneficiaries are also responsible for their Part B premium and any premiums for Medigap coverage to meet their individual needs.

Part D Supplemental Premium:  The Part D Supplemental Premium covers any enhanced benefits that may be offered by a plan above and beyond the basic (standard) Part D benefit.  These benefits may include extra coverage in the coverage gap, lower copayments than the standard benefit, coverage of non-Part D drugs.  Note: the Part D Supplemental Premium is net of any Part A/B rebates applied to "buy down" the drug premium for Medicare Advantage plans.”

Although only the “total premium” is important to most people considering a Medicare Advantage plan (MAPD) or Medicare Part D plan (PDP), we also provide the Part D Base Premium and Supplemental Premium information within our Medicare Part D Plan Finder (https://PDP-Finder.com) and Medicare Advantage Plan Finder (https://MA-Finder.com) since this information can be used by Medicare beneficiaries to understand how much they will pay per month for a Medicare Part D plan if they are eligible for the full 100% Low-Income Subsidy (LIS).

Likewise, the Q1Medicare plan finders show a table listing the monthly premiums for people who are qualified for only 75% or 50% or 25% of  the Low-Income Subsidy or Extra Help (based on their income or financial resources).

The Base and Supplemental Medicare Part D Premium and Medicare Part D Extra Help

A person who is qualified for full Extra Help or 100% LIS benefits will pay either no Medicare plan premium ($0 depending on the plan) or the person will pay only a portion of the “full premium” that is approximately above the state's Benchmark $0 LIS Premium. 

You can see more about a state’s 2022 benchmark premium in our article "2022 State Low-Income Subsidy Benchmark Premium Amounts - with a comparison of benchmark changes since 2006" here: https://Q1News.com/886.html.

Example:  Your Medicare Part D premium when you are qualified for 100% LIS or full Extra Help

If you qualify for 100% of the LIS subsidy, and you have chosen to enroll into a Medicare Part D prescription drug plan that does not qualify for your state's Low-Income Subsidy $0 monthly premium, then you are responsible for a portion of your monthly premium that is above the state's benchmark premium.

For example, the 2020 Florida $0 LIS Benchmark Premium is $28.47 and if you are qualified for full Extra Help and enrolled in a "basic" Medicare Part D plan with a premium below (or even slightly over) the state benchmark premium, you would pay a $0 premium.

So, if you chose to enroll in the 2020 SilverScript Choice (PDP) Medicare Part D plan that has a $25.20 premium, you would pay a $0 premium.

However, in the same situation, if you enrolled into the 2020 Humana Basic Rx Plan (PDP) that has a $40 premium, you would pay $11.50 per month premium (the $40 premium - the $28.47 state benchmark premium).

Example:  Your Medicare Part D premium when you are qualified for less than 100% LIS

If you no longer qualify for full Extra Help Benefits (less than 100%), you may be paying a higher portion of your Medicare Part D plan's premium -  even when the Medicare Part D prescription drug plan qualifies for the $0 monthly Low-Income Subsidy premium.

Using the same above example of the Florida 2020 SilverScript Choice (PDP) Medicare Part D plan that has a $25.20 premium, you would pay a $0 premium with full (100%) Extra Help benefits.

But, if you were eligible for only partial Extra Help benefits, you would pay a higher premium (although still less than the full $25.20 premium).  In our example, if you qualified for 50% Extra Help, you would pay a premium of $12.60.


Example:  Paying the premium balance when you are qualified for full Extra Help, but you have chosen a Medicare Part D plan with a premium well above the state benchmark premium.

In this example, if you qualify for full Extra Help benefits, and your state has a LIS $0 premium benchmark of $28.50, - and you wish to join a Medicare Part D plan with a premium of $58 – you will not pay the full $58 premium with your LIS status, but instead, you will pay only a portion of the total premium.

In this example, let us assume that, of the $58 total premium, $51 is the base premium and this base premium is over the state’s $29 benchmark premium – meaning you pay $29.50.


So if you receive 100% Extra Help (or are dual Medicare/Medicaid eligible), you will pay the portion of the Base Premium over the benchmark (the amount over the base premium that is not covered by the state benchmark premium + the supplemental premium) or, as shown in the graphic: ($51 Base Premium - $28.50 Benchmark Premium) + $7 Supplemental Premium = $29.50, your premium with 100% LIS eligibility.