No.  No matter what Medicare Part D drug plan you choose, you will have no cost-sharing for formulary Medicare Part D drugs once meeting your annual total out-of-pocket spending limit and enter Catastrophic Coverage.

Important:  Starting in 2024, the Inflation Reduction Act (IRA) eliminated cost-sharing for formulary Part D drugs in the Catastrophic Coverage phase.  This means, if you exit the 2024 Donut Hole and enter the Catastrophic Coverage phase, you will pay nothing more (cost-sharing will be $0) for all formulary Medicare Part D drugs through the remainder of the year.

2024 Medicare Part D coverage


Another Important Update:  2024 is the last year for the Coverage Gap or Donut Hole.  Starting in 2025, the Donut Hole will no longer be a part of your Medicare Part D coverage. 

Starting in 2025, the Inflation Reduction Act (IRA) eliminates the Coverage Gap (Donut Hole).  In 2025 and beyond, Medicare Part D beneficiaries will stay in the Initial Coverage phase until their out-of-pocket spending for Part D formulary drugs (TrOOP) reaches the maximum out-of-pocket spending limit for Part D formulary drugs (RxMOOP) - which is set at $2,000 for 2025.  After reaching RxMOOP, Medicare Part D beneficiaries will enter Catastrophic Coverage and have a $0 copay (no additional costs) for all formulary Medicare Part D drugs through the remainder of the year.

2025 Medicare Part D coverage

Historical Review: Before 2024

If you reached the Catastrophic Coverage phase in 2023 or before, you paid the greater of (1) a flat fee (set annually) or (2) 5% of the plan's negotiated retail drug cost for your formulary medications, depending on the type of drug -- generics or preferred brand drugs that are multi-source drugs vs. all other drugs.

And before 2024, Catastrophic Coverage cost-sharing was the same for all Medicare Part D plans - but, Medicare plans had different retail drug prices that affected your drug costs in the pre-2024 Catastrophic Coverage phase.

Medicare Part D coverage 2006 to 2023


For example, in 2023, you paid the higher of either 5% of retail prices or $10.35 for brands or $4.15 for generics in Catastrophic Coverage.

So if you used a single-source, brand drug with a $100 retail price, you paid $10.35 since the fixed co-pay of $10.35 was more than (5% of $100) or $5.  If another brand drug you used had a $150 retail cost, you still paid $10.35 since this amount is still higher than (5% of $150) or $7.50.  In such an example, the retail drug cost did not affect your fixed Catastrophic Coverage cost.

However, if "Medicare Part D Plan AAA" has a retail cost for Drug X of $400, you would pay $20 in the Catastrophic Coverage phase (5% of $400).  But if "Medicare Part D Plan BBB" has a retail cost for the same Drug X of $500, you would pay $25 (5% of $500) - or $5 more than the cost with Medicare Part D Plan AAA.

As a real-life example, a popular Medicare Part D drug with a high retail price (assume $6,000), might cost 33% of retail during the Initial Coverage Phase (about $1,980), 25% of retail in the Coverage Gap or Donut Hole ($1,500), and 5% of retail in Catastrophic Coverage ($300).  If the retail cost of the medication for another Medicare Part D plan was $7,000, then you would pay $350 in Catastrophic Coverage.


In summary:  If you reached the pre-2024 Catastrophic Coverage phase, you found that your Medicare Part D Catastrophic Coverage phase had the same cost-sharing structure as every other Medicare Part D plan.  However, your actual drug costs in this phase varied between different drug plans since your Catastrophic costs might be based on your Medicare Part D plan's negotiated retail drug price - and retail drug prices varied between Medicare Part D prescription drug plans.

Again, keep in mind that 2023 was the last year that Medicare Part D beneficiaries will pay cost-sharing in the Catastrophic Coverage phase.  For plan year 2024, the Inflation Reduction Act (IRA) of 2022 eliminates beneficiary cost-sharing in the Catastrophic Coverage phase.