Medicare prescription drug coverage is available through two different plan structures. A Prescription Drug Plan (PDP) is a standalone plan that adds drug coverage to Original Medicare (Parts A and B). A Medicare Advantage Prescription Drug plan (MAPD) is a Medicare Advantage plan that includes drug coverage as part of a bundled package. You cannot enroll in both a PDP and an MAPD at the same time.
Side-by-Side Comparison
| Feature | PDP (Standalone Part D) | MAPD (Medicare Advantage + Drug) |
|---|---|---|
What it pairs with | Original Medicare (Parts A and B) | Medicare Advantage (Part C) |
Medical coverage | Original Medicare (80% after deductible) | Plan-specific network and cost-sharing |
Drug coverage | Yes | Yes (built in) |
Extra benefits (dental, vision, hearing) | No | Often yes |
Provider network restrictions | None for medical care | Yes (HMO or PPO network) |
Out-of-pocket maximum | None for medical (Part A/B) | Annual cap on all covered services |
Medigap compatibility | Yes | No |
Monthly premium | Part B + PDP premium | Often lower combined premium |
When a PDP Makes More Sense
A standalone PDP is the right choice if you want to stay on Original Medicare and pair it with a Medigap (Medicare Supplement) plan. Medigap plans are not compatible with Medicare Advantage, so if you want comprehensive coverage with no network restrictions and predictable costs, the combination of Original Medicare + Medigap + PDP is the traditional approach.
When an MAPD Makes More Sense
An MAPD can be a good fit if you want a single plan that covers medical, hospital, and drug costs, often with extra benefits like dental and vision. MAPD plans typically have lower monthly premiums than the Original Medicare + Medigap + PDP combination, but they come with provider networks and may have higher out-of-pocket costs if you need significant care.
$2,000 Out-of-Pocket Cap on Part D in 2026
Starting in 2026, the maximum out-of-pocket limit for Part D drug costs is $2,000 per year. This cap applies to both PDPs and MAPDs. Once you reach this limit, your plan covers 100% of covered drug costs for the rest of the year.
Switching Between PDP and MAPD
You can switch between a PDP and an MAPD during the Annual Enrollment Period (October 15 through December 7) each year, with changes taking effect January 1. If you want to switch from an MAPD back to Original Medicare with a Medigap plan, keep in mind that Medigap insurers can use medical underwriting outside of guaranteed issue periods, which may affect your eligibility.
Can I have a PDP and a Medicare Advantage plan at the same time?
No. If you enroll in a Medicare Advantage plan that includes drug coverage (MAPD), you cannot also enroll in a standalone PDP. If you enroll in a Medicare Advantage plan without drug coverage (MAPD-only plans are rare), you may be able to add a PDP, but this is uncommon.
What happens to my PDP if I switch to Medicare Advantage?
Your PDP will be automatically disenrolled when your Medicare Advantage plan takes effect. You do not need to cancel it separately.
Are formularies the same for PDPs and MAPDs?
No. Each plan has its own formulary (list of covered drugs) and tier structure. Always check that your specific medications are covered at an acceptable cost tier before enrolling in any plan.
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