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How to Read an Explanation of Benefits (EOB): A Line-by-Line Guide

EOBCheck · Updated August 25, 2026 · 8 min read

An EOB is not a bill. It's your insurance company's explanation of how it processed a claim — and it's usually the single most useful document for figuring out what you actually owe. Here's what every field on it actually means.

The header: who, what, when

At the top, you'll typically find the patient name, the provider or facility name, the date of service, and a claim number. Keep the claim number — you'll need it if you ever call your insurer about this specific visit.

The core numbers, field by field

Amount billedWhat the provider originally charged for the service.
Allowed amountThe negotiated rate your insurance plan actually recognizes — usually lower than the billed amount.
Amount paid by insuranceWhat your insurer actually paid the provider.
Patient responsibilityWhat your insurer calculates that you owe — this is the figure to compare against your bill.
Deductible / copay / coinsuranceThe breakdown of why you owe what you owe, based on your specific plan's rules.

"Not a bill" — and why that matters

Almost every EOB says "this is not a bill" somewhere on it, in bold. That's because the EOB's job is only to tell you how the claim was processed — the actual request for payment comes separately from your provider. Medicare.gov's own guidance describes the EOB as a notice to review for mistakes, not a request for payment. The two documents should agree on the patient responsibility figure. When they don't, that's the exact gap worth investigating (see our guide to why bills and EOBs don't match).

Allowed amount vs. billed amount: the part people misunderstand

If your provider is in-network, you're generally not responsible for the difference between the billed amount and the allowed amount — that gap gets written off under your insurer's contract with the provider. If a bill asks you to pay based on the full billed amount instead of the allowed amount, that's a specific, checkable red flag.

Quick math check: Allowed amount − insurance paid should equal patient responsibility. If those three numbers on your own EOB don't add up, call your insurer and ask them to explain the discrepancy before you assume the bill is correct.

Remark codes and denial codes

Many EOBs include a short code next to a line item (sometimes just 2–3 letters or numbers) with a matching explanation elsewhere on the page or a linked glossary. These explain why something was denied, reduced, or adjusted — for example, "not a covered service" versus "missing prior authorization" are very different problems with very different next steps.

What to do once you've read it

  1. Find the patient responsibility figure.
  2. Compare it directly to what your provider's bill says you owe.
  3. If they match (within a few dollars), you're likely fine to pay.
  4. If they don't, note the exact dollar difference before calling anyone — it makes the conversation much faster.

Skip the manual math

EOBCheck takes your EOB's numbers and your bill's numbers and does this comparison for you automatically — flagging exactly where they disagree and drafting a letter to ask why.

Compare my bill and EOB — free

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