Medicare 2026

Your Monthly Part D Explanation of Benefits: How to Read It and Spot Errors

If you have Medicare drug coverage, your plan sends you a statement called an Explanation of Benefits, or EOB, the month after you fill prescriptions. It isn't a bill. It's a summary of what happened at the pharmacy counter: which drugs you got, what the plan paid, what you paid, what coverage stage you're in, and how close you are to the yearly out-of-pocket cap. Learning to read it — and skim it for mistakes — is one of the simplest ways to protect yourself from overpaying.

When the EOB shows up and what triggers it

Federal rules require your plan to send an EOB no later than the end of the month after any month you used your drug benefit. If you didn't fill anything in a given month, you may not get a statement that month. Many plans let you view EOBs online as soon as claims process, which is often faster than the mailed version.

What has to be on it

At minimum, an EOB lists each prescription you filled and the amount paid, and it tells you that you have the right to request an itemized statement from the plan. For each drug, it shows what the plan paid and what you paid, plus any cumulative percentage increase in that drug's negotiated price since your first claim of the year. When lower-cost alternatives exist on your plan's formulary, the EOB must flag them — that's a built-in nudge to talk with your prescriber about whether a cheaper therapeutic option would work for you.

The EOB also has to include any negative formulary changes the plan is required to tell you about: for example, a drug you take being removed from the formulary or moved to a higher tier. If you see one of those notices, don't ignore it — it can change what you pay next month.

The running totals: deductible, out-of-pocket cap, and coverage stage

This is the part most people skip, and it's the most useful. The EOB must show cumulative year-to-date totals compared with your plan's deductible and the annual out-of-pocket threshold, along with your year-to-date out-of-pocket (incurred) costs. The out-of-pocket cap is $2,100 in 2026 and $2,400 in 2027. The most any Part D plan may charge as a deductible in 2027 is $700, though many plans set it lower.

Your EOB also shows which coverage stage you're in. Once you — or others paying on your behalf, including Extra Help — reach the yearly cap, you pay $0 for covered Part D drugs for the rest of the calendar year, and the EOB will reflect that you've reached catastrophic coverage. If your totals look off compared with receipts you've kept, that's a red flag worth a phone call.

How to spot errors

Walk through the EOB with this quick checklist:

• Did you actually fill every prescription listed? Watch for drugs you never got or refills you didn't request.
• Are the quantities and days' supply right?
• Does what you paid at the counter match what the EOB says you paid?
• Did a drug's price jump since earlier in the year? The EOB will tell you the percentage.
• Is your running out-of-pocket total believable given what you've spent?
• Are there formulary change notices for drugs you take?

If something's wrong, contact your plan first — the member services number is on the EOB. If you suspect fraud (billing for drugs you didn't receive, a pharmacy billing twice), call the Medicare Drug Integrity Contractor at 1-877-7SAFERX (1-877-772-3379).

Enrollment windows worth knowing

The Annual Enrollment Period for 2027 coverage runs October 15 – December 7, 2026, with changes effective January 1, 2027. If you have Medicaid or qualify for Extra Help, since 2025 you have a monthly Special Enrollment Period to move to Original Medicare with a stand-alone Part D plan or to switch stand-alone Part D plans. Full-benefit dual-eligible individuals can join an integrated D-SNP in any month. The Part D base beneficiary premium for 2027 is $41.33, a national figure used to calculate the late-enrollment penalty; actual plan premiums are set plan by plan.

A quick note on the broader program: the Social Security Administration announced a 3.6 percent cost-of-living adjustment for benefits payable beginning January 2027. The 2027 Part B standard premium and deductible, and the IRMAA income brackets, had not been announced at the time of writing — CMS typically announces those figures in the fall.

Medicare Advantage vs. Original Medicare + Medigap

If your drug coverage comes through a Medicare Advantage plan with Part D built in, your EOB works the same way for the drug portion. Choosing between Medicare Advantage and Original Medicare paired with a stand-alone Part D plan and (optionally) a Medigap policy is a personal trade-off: Advantage plans often bundle extras and use networks, while Original Medicare plus Medigap generally offers broader provider access with separate premiums. Neither is universally better; it depends on your doctors, your drugs, your travel, and your budget.

Where to go next

For official program rules, plan comparisons using your own drug list, and help understanding your coverage, visit Medicare.gov or call 1-800-MEDICARE (1-800-633-4227), available 24/7. Keep your EOBs — they're your paper trail, and a few minutes of review each month can save real money by year's end.