Pharmacy Receipt Doesn't Match Part D EOB

What This Means

You picked up a prescription at the pharmacy and paid a certain amount. But when you got your Part D Explanation of Benefits (EOB) in the mail or online, the amount listed as “your cost” was different from what you actually paid. This is confusing — and it matters, because the wrong amount can affect how much credit you get toward your annual out-of-pocket cap.

The good news is that this kind of discrepancy is usually a billing issue, not a coverage denial. In most cases, a phone call to your Part D plan or pharmacy can clear it up. If you overpaid, you are entitled to a refund.

It is important to sort this out, though. Under the Inflation Reduction Act, Part D plans now have a $2,100 annual out-of-pocket cap. Your share of the plan’s price should count toward that limit — but only if the claim is processed through your Part D benefit, and any amount you paid above the plan’s price does not count.

Why This Happens

• The pharmacy used a different price than your plan’s negotiated rate. Pharmacies sometimes charge a “usual and customary” price at the register that differs from the lower rate your Part D plan negotiated. The plan later adjusts the claim to reflect the correct amount.
• Your plan retroactively adjusted the claim after the point of sale. Part D plans can change the pricing on a claim days or weeks after you filled the prescription. When this happens, your EOB will show a different cost than what you paid at the counter.
• A discount card was used instead of your Part D benefit. If the pharmacy ran your prescription through a discount card (like GoodRx or a manufacturer coupon) instead of your Part D plan, the price you paid may be lower, but the payment doesn’t count toward your annual out-of-pocket cap automatically, because your plan never sees it. For a drug your plan covers, bought at a network pharmacy, you can send your plan the receipt and ask it to process the purchase as a claim — see When Part D Costs More Than Cash.
• The pharmacy applied the wrong cost-sharing tier. Part D plans organize drugs into tiers (generic, preferred brand, non-preferred, specialty). If the pharmacy billed at the wrong tier, your copay or coinsurance amount will be wrong.
• You moved into a different Part D payment phase. Your cost-sharing changes as you move through the 2026 Part D phases — the deductible, then initial coverage, then the catastrophic phase once your out-of-pocket spending reaches the $2,100 annual cap (the old “coverage gap” / donut hole was eliminated in 2025). If the pharmacy’s system wasn’t updated or the timing was off, you may have been charged based on the wrong phase.

Should You Appeal?

What To Do Next

1. Gather your documents. Find your pharmacy receipt and your Part D EOB for the same prescription fill. Look for the fill date, drug name, and the amount listed as “patient pay” or “your cost” on each document.
2. Compare the two amounts. If the receipt shows you paid more than the EOB says you should have, you are likely owed a refund. If the receipt shows you paid less, your plan may send you a bill for the difference — but check that the EOB amount is correct first.
3. Call your Part D plan. The phone number is on the back of your plan membership card or on the EOB itself. Tell them the amounts don’t match and ask them to explain the difference. If you overpaid, ask for a refund or a corrected claim.
4. Ask the pharmacy to reprocess, or submit the receipt yourself. If the pharmacy used a discount card instead of your Part D plan, ask them to reverse the transaction and reprocess it through your Part D benefit. If that’s not possible, and the drug is one your plan covers and you bought it at a network pharmacy, you can instead send your plan the receipt and ask it to process the purchase as a claim (CMS Prescription Drug Benefit Manual, chapter 14, section 50.4.3) — either way, your share then counts toward your $2,100 annual out-of-pocket cap (on the receipt route, based on the price you actually paid, and never more than your plan’s price). See When Part D Costs More Than Cash for the full process.
5. Appeal or file a grievance, depending on who refused. If your plan refuses to pay you back, ask it for a redetermination within 65 days of the date on its written decision. If the pharmacy won’t fix a billing error, file a grievance with your Part D plan within 60 days of the incident (42 CFR 423.564(d)(2)); the plan must resolve it within 30 days (it can take up to 14 more days if it tells you why in writing).
6. Get free help. Contact your State Health Insurance Assistance Program (SHIP) for one-on-one counseling, or call 1-800-MEDICARE (1-800-633-4227). You can also visit Medicare.gov to look up your plan’s grievance process.

Sources

• Medicare.gov: Costs for Medicare drug coverage — the 2026 Part D payment phases (deductible → initial coverage → catastrophic) and the $2,100 annual out-of-pocket cap.
• Medicare.gov: Appeals in a Medicare Drug Plan — how coverage determinations and appeals work in a Part D plan.
• CMS: Part D Grievances — the grievance process (30-day standard / 24-hour expedited resolution).
• CMS Prescription Drug Benefit Manual, Chapter 14, §50.4.3 — Direct Member Reimbursement (rev. 09-17-2018) — beneficiaries who pay cash or use a discount card at an in-network pharmacy for a covered drug can submit the receipt for reimbursement; once processed, their cost-sharing counts toward the deductible and out-of-pocket cap.
• 42 CFR 423.564: Grievance procedures — the Part D grievance timeframes in regulation.
• CMS: Medicare Prescription Payment Plan — spreading your out-of-pocket drug costs into capped monthly payments.

Frequently Asked Questions