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 to Choose the Best Medicare Part D Plan for Your Prescriptions
Last Modified: 10/01/2026 | Reviewed by Keith Armbrecht (NPN 634015)
Quick Summary
The best Medicare drug plan usually isn’t the plan with the lowest premium. It’s the plan that provides the best total cost and coverage for your specific prescriptions and pharmacy.
When comparing Part D plans, enter your exact:
- Medications
- Dosages
- Frequency
- Preferred pharmacy
Then compare your estimated annual cost.
Key Facts
- Part D formularies vary.
- Drug tiers vary.
- Premiums vary.
- Deductibles vary.
- Pharmacy networks vary.
- Preferred pharmacies may reduce costs.
- Prior authorization can apply.
- Step therapy can apply.
- Quantity limits can apply.
- The cheapest premium isn’t necessarily the cheapest plan.
- Part D plans should be reviewed every year.
Step 1: Make an Exact Medication List
For every prescription, write down:
Drug name
strength
quantity
how often you refill it
Don’t simply list:
“Blood pressure medication.”
The exact medication matters.
Step 2: Enter Your Pharmacy
Your pharmacy can dramatically affect plan cost.
Compare:
- Your current pharmacy
- Preferred network pharmacies
- Mail-order options
Step 3: Check the Formulary
Verify that every prescription is covered.
Then determine:
- Drug tier
- Copay
- Coinsurance
- Restrictions
Step 4: Check for Restrictions
Look for:
Prior Authorization
The plan may require approval before paying.
Step Therapy
You may have to try a different medication first.
Quantity Limits
The plan may restrict how much medication it covers during a period.
Step 5: Compare Total Annual Cost
Don’t rank plans only by:
Monthly premium
Instead compare:
Annual premium
plus:
Deductible
plus:
Expected prescription costs
A $10-per-month plan can cost more overall than a $35-per-month plan if your medications are much more expensive under the cheaper-premium plan.
Step 6: Recheck Every Year
Part D plans can change:
- Premium
- Formulary
- Tiers
- Pharmacy relationships
- Drug restrictions
Your medications can change too.
Review Part D during Medicare Open Enrollment each year.
Video Explanation from Keith
How I Choose a Medicare Part D Plan
Keith's Take
I don’t pick drug plans based on the insurance company.
I don’t pick them based on the premium.
I pick them based on:
The drugs you actually take.
Give me your medication list and preferred pharmacy and then compare the total annual cost.
That’s the number I care about.
And repeat the process every year.
Keith Armbrecht
Medicare on Video
Frequently Asked Questions
Q. What's the best Part D plan?
A. It depends on your prescriptions and pharmacy.
Q. Should I choose the lowest premium?
A. Not necessarily.
Q. Does every plan cover the same drugs?
A. No.
Q. Does pharmacy choice matter?
A. Yes.
Q. What is a preferred pharmacy?
A. A pharmacy where a plan may offer lower negotiated cost sharing.
Q. Should I check prior authorization?
A. Yes.
Q. Should I review my plan every year?
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.
