A 71-year-old retiree in Ohio stayed on Original Medicare when he aged in. He wanted the freedom to see any doctor who takes Medicare, so he paired Part A and Part B with a Medigap policy and a stand-alone Part D prescription drug plan (a PDP). That choice still buys him the widest provider access in American health care. It is also, quietly, becoming the more expensive way to get drug coverage, and the cushion that has been hiding the gap goes away at the end of this year.
If you are on Original Medicare with a stand-alone PDP, the next open enrollment window (October 15 to December 7) is the one to take seriously. If you are on a Medicare Advantage plan with built-in drug coverage, most of what follows will not touch your wallet in 2027.
The Drug-Premium Gap Most Original Medicare Enrollees Never See
Stand-alone Part D plans and the drug coverage bundled inside Medicare Advantage plans (MA-PD) are priced on completely different economics. MA plans receive rebate dollars from Medicare that insurers can redirect to “buy down” the drug portion of the premium. Stand-alone PDPs cannot.
The result, per KFF’s analysis of CMS data: the average monthly PDP premium in 2026 is about $36, while the average drug-coverage premium inside a Medicare Advantage plan is about $8. That is more than four times the cost for the same category of benefit, before anyone fills a prescription. Enrollment tells you people are noticing. PDP enrollment rose from 22.8 million in 2024 to 24.9 million in 2026, even as many retirees migrated toward Advantage plans for the drug economics.
The Hidden Cushion: A Two-Year CMS Demonstration Ending After 2026
The PDP average would already be higher without a temporary program most enrollees have never heard of. CMS’s Part D Premium Stabilization Demonstration ran across 2025 and 2026 to keep stand-alone drug premiums from spiking as the Inflation Reduction Act reshaped Part D’s benefit structure.
The mechanics, per KFF citing CMS and MedPAC:
- The demonstration reduced the Part D base beneficiary premium by $15 in 2025 and $10 in 2026.
- It capped year-over-year monthly premium increases at $35 in 2025 and $50 in 2026.
- MedPAC estimates it reduced the average monthly PDP premium by $26 in 2025 and $16 in 2026.
- Total federal outlay across the two years: $9.8 billion.
CMS is ending the demonstration after 2026. Plan-specific 2027 premiums land in the fall, so no one can quote a number yet. But the direction is straightforward: without the base-premium reduction and without the year-over-year cap, PDP premiums in 2027 face upward pressure that MA-PD drug premiums largely will not.
Why This Widens an Already-Wide Cost Gap
The household math is more useful. The average PDP premium already costs $28 more per month than the drug portion of an MA-PD plan, a difference of $336 a year. MedPAC estimates the temporary demonstration lowered average PDP premiums by another $16 a month in 2026. That does not mean every premium will rise by $16 in 2027, but it shows how much federal support is leaving the market. Final plan prices arrive in September.
None of this makes Original Medicare the wrong choice. Any provider that accepts Medicare will see you. There are no networks, no prior authorization for basic care, and pairing with Medigap caps most of your medical exposure. Those benefits are real and stay real in 2027. The point is that the drug-plan side of the ledger has been getting cheaper artificial support, and that support is going away.
What to Do at Open Enrollment
- Re-shop your PDP every year, and especially this year. A plan that made sense in 2026 may not once the demonstration expires. Use the Medicare Plan Finder at Medicare.gov, enter your exact prescriptions and preferred pharmacy, and compare total annual cost (premium plus deductible plus copays), not just the premium.
- Model an MA-PD comparison carefully. Price out at least one Medicare Advantage plan available in your county, and weigh its drug premium against the loss of any-provider access. If your doctors and hospitals are all in-network and you rarely travel, the drug savings may matter more than the network cost.
- Do not switch reflexively. Moving from Original Medicare plus Medigap into an Advantage plan is easy. Moving back later usually means applying for Medigap under medical underwriting in most states, where you can be denied. Treat the switch as closer to one-way than it feels.
Contact [email protected] for any questions or corrections.
Top Gaining Stocks
Top Losing Stocks