Creditable Prescription Drug Coverage Explained
Creditable prescription drug coverage is drug coverage that’s expected to pay, on average, at least as much as Medicare’s standard Part D prescription drug coverage.
How Do Medicare Prescription Drug Plans Work?
Last Modified: 10/06/2026 | Reviewed by Keith Armbrecht (NPN 634015)
Quick Summary
Medicare Part D plans help pay for outpatient prescription medications, but every plan can have a different formulary, premium, deductible, pharmacy network and cost-sharing structure.
That’s why there isn’t one “best” Medicare drug plan for everyone.
The best plan for you depends heavily on:
Your medications
dosages
and
pharmacy.
Key Facts
- Part D plans are sold by private Medicare-approved insurers.
- Standalone Part D plans work with Original Medicare.
- Most Medicare Advantage plans include Part D.
- Each plan has a formulary.
- Formularies divide drugs into tiers.
- Lower tiers often cost less.
- Preferred pharmacies may provide lower prices.
- Prior authorization may apply.
- Step therapy may apply.
- Quantity limits may apply.
- Plans can change from year to year.
- Annual review is important.
Step 1: The Formulary
Every drug plan has a list of covered medications called a:
Formulary
The formulary tells you:
- Whether your drug is covered
- Which tier it’s on
- What restrictions apply
Step 2: The Deductible
Some plans have a deductible.
For 2026, a Medicare drug plan can’t have a deductible higher than:
$615
Some plans charge less or no deductible at all.
Step 3: Drug Tiers
Plans commonly organize covered prescriptions into cost tiers.
For example:
Tier 1 — preferred generic
Tier 2 — generic
Tier 3 — preferred brand
Tier 4 — non-preferred drug
Tier 5 — specialty
Actual tier structures vary by plan.
Step 4: Pharmacy Network
Your pharmacy matters.
The same drug in the same Part D plan can sometimes cost less at:
A preferred pharmacy
than at:
A standard network pharmacy.
Step 5: Coverage Rules
A plan may require:
Prior Authorization
Approval before the plan covers a medication.
Step Therapy
Trying another drug first before the plan covers a particular drug.
Quantity Limits
Limits on how much medication is covered within a given period.
2026 Part D Out-of-Pocket Protection
In 2026, covered Part D drug out-of-pocket spending is capped at:
$2,100
Once you reach that threshold, you generally pay:
$0
for covered Part D drugs for the rest of the calendar year.
Medicare Prescription Payment Plan
Medicare also offers a payment option that allows eligible drug-plan members to spread qualifying out-of-pocket prescription costs across the calendar year.
It changes when you pay, not the total amount you owe.
Video Explanation from Keith
How Medicare Part D Drug Plans Really Work
Keith's Take
I never want someone picking Part D because:
“My friend has this plan.”
Your friend’s prescriptions probably aren’t identical to yours.
I want your exact drug list entered into Medicare’s plan comparison system with:
drug name
dosage
frequency
and
pharmacy.
Then compare estimated total annual cost—not simply the monthly premium.
Keith Armbrecht
Medicare on Video
Frequently Asked Questions
Q. Does every Part D plan cover the same drugs?
A. No.
Q. What is a formulary?
A. The plan's list of covered drugs.
Q. What is the maximum deductible in 2026?
A. $615.
Q. What is the 2026 Part D out-of-pocket limit?
A. $2,100 for covered Part D drugs.
Q. Does pharmacy choice matter?
A. Yes.
Q. Can plans require prior authorization?
A. Yes.
Q. Can drug coverage change each year?
A. Yes.
Q. Should I review Part D annually?
A. Yes.
Official Government Sources
Explore Related Guides
Medicare Part D Tiers, Copays and Coinsurance Explained
Medicare drug plans commonly divide covered medications into tiers, with lower-tier drugs generally costing less and higher-tier drugs generally costing more.
