Catastrophic Coverage is paid by a combination of your Medicare Part D plan, the government and if your purchase was a brand-name drug, then a portion is paid by the drug manufacturer.  Once you enter Catastrophic Coverage, you do not pay anything for your formulary drugs for the remainder of the year.

In 2025, the Inflation Reduction Act (IRA) eliminated the Coverage Gap and extended the Initial Coverage phase until a person has spent $2,000 out-of-pocket for Part D formulary drugs.  The $2,000 represents the prescription drug maximum out-of-pocket spending limit (RxMOOP).  And as stated above, when a person reaches the RxMOOP ($2,100 in 2026), the plan member enters Catastrophic Coverage and will not have any additional costs for Part D formulary drugs for the remainder of the year.

Also in 2025, the IRA changed the percentage of the drug costs allocated to the brand-name drug manufacturer, Medicare Part D plan, and the federal government, see example table below.


* 25% coinsurance or cost-sharing until you reach the $2,000 RxMOOP, then your Part D formulary drug costs are $0 for the remainder of the year.
** The 10% brand-name drug manufacturer portion paid in the 2025 Initial Coverage phase (after the standard deductible) does not apply toward the $2,000 TrOOP threshold (https://www.cms.gov/files/document/manufacturer-discount-program-final-guidance.pdf).
**** Starting in 2025, the Coverage Gap (or Donut Hole) no longer exists for plan members.  A plan member will stay in the Initial Coverage phase until exceeding the plan's $2,000 out-of-pocket spending threshold and then enter Catastrophic Coverage where for the remainder of the year, the person will have no out-of-pocket costs for formulary drugs.  As noted below, the $2,000 out-of-pocket threshold or RxMOOP can change every year.

Medicare Part D coverage 2025 and beyond



Question:  Can the $2,000 RxMOOP change every year?

Yes.  Like other Medicare Part D plan parameters, the annual $2,000 RxMOOP can (and probably will) change every year.  Currently, the Catastrophic Coverage threshold (or RxMOOP) is predicted to decrease over time.

Year	Catastrophic threshold (RxMOOP)
2024	$8,000
2025	$2,000
2026	$2,100
2027	$2,050
2028	$2,000
2029	$1,950

Prior to plan year 2024, Medicare Part D plan members who had high medication costs would pay roughly 5% of the formulary drug's retail cost during the Catastrophic Coverage phase.

Of the remaining 95% of the total retail drug cost, 80% of the cost was paid by the federal government or Medicare’s reinsurance subsidy, 15% of the retail drug cost was paid by the Medicare prescription drug plan (Medicare Part D plan or Medicare Advantage plan).

So, as illustrated in the example below, if you reached the 2023 Catastrophic Coverage phase and buy a brand-name formulary drug with a $300 retail cost, you paid $15 for the drug, the federal government paid $240, and the Medicare Part D prescription drug plan paid $45.

In 2024, the Inflation Reduction Act (IRA) eliminated beneficiary cost-sharing in the Catastrophic Coverage phase.

A Medicare Part D plan member did not have any out-of-pocket costs after reaching the plan's total out-of-pocket threshold (TrOOP) of  $8,000.  Therefore, the 2024 TrOOP became the prescription drug maximum out-of-pocket spending threshold (RxMOOP).

Below is a chart showing how example formulary drug purchases were paid throughout your Medicare Part D plan coverage -- using the CMS defined standard benefit Medicare Part D plan with a fixed 25% coinsurance for calculating cost-sharing.


* 25% coinsurance or cost-sharing
** 75% Brand-name Donut Hole Discount
*** 75% Generic Donut Hole Discount
**** In 2024, the Catastrophic Coverage phase still existed, but plan members did not have any out-of-pocket costs for formulary drugs after reaching the plan's $8,000 total out-of-pocket threshold (TrOOP).

2024 Medicare Part D coverage




Question: How did the Catastrophic Coverage work prior to 2024?

Prior to 2024, in the Catastrophic Coverage phase, you paid either a flat copay fee (set annually) or 5% of the plan's negotiated retail drug cost (whichever was greater) for your formulary medications, depending on the type of drug -- generics or preferred brand drugs that are multi-source drugs vs. all other drugs.

For example, in 2023, you paid the higher of either 5% of the drug's retail price or $10.35 for brand name drugs or $4.15 for generic drugs in Catastrophic Coverage.

So in 2023, if you purchased a brand-name drug with a retail price of $100 in the Catastrophic Coverage phase, you paid $10.35 for the prescription fill since the fixed $10.35 brand-name drug copay is higher than 5% of the $100 retail drug price (or $5).  But, if you purchased a brand-name formulary drug with a retail cost of $300, you paid $15 in the 2023 Catastrophic Coverage phase since 5% of $300 ($15) is more than the 2023 fixed copay of $10.35.

2023 Medicare Part D coverage

More Part D History:  Simple example of 2023 Medicare Part D plan coverage costs

Here is how example formulary drug purchases are calculated throughout your 2023 Medicare Part D plan (using the CMS defined standard benefit Medicare Part D plan as a guide).


* 25% coinsurance or cost-sharing
** 75% Brand-name Donut Hole Discount
*** 75% Generic Donut Hole Discount
**** In 2023, you paid 5% of retail or $10.35 for brand drugs whatever is higher or 5% of retail or $4.15 for generic or multi-source drugs whatever is higher (80% paid by Medicare, 15% paid by Medicare plan, and around 5% by plan member)


See:
https://www.democrats.senate.gov/imo/media/doc/inflation_reduction_act_of_2022.pdf
https://www.cms.gov/files/document/2025-announcement-pdf.pdf
https://www.cms.gov/oact/tr/2025