Your EOB in plain English
EOBs are confusing by design — cryptic codes, an “amount you may owe,” and numbers that never seem to add up. Here’s the thing: an EOB isn’t a bill — it’s your insurer’s summary of a claim, and we’ll translate every line of yours into plain English.
Look for short codes on each line of your EOB — things like PR-1, PR-2, CO-45, or N130. You can paste a whole line; we’ll find the codes.
How to read your EOB
Most EOBs show the same columns for every service. Here’s a typical line and what each number means. The only number you may actually be billed for is the last one.
| Line on your EOB | Example | What it means for you |
|---|---|---|
| Amount billed | $400.00 | What the provider charged. This is not what you owe. |
| Allowed amount | $250.00 | The most your plan will pay for this service under its contract. |
| Plan discount (CO-45) | −$150.00 | Written off by your in-network provider. You do not owe this. |
| Plan paid | $200.00 | What your insurer paid the provider. |
| Your responsibility (PR) | $50.00 | Your share — deductible, copay, or coinsurance. This is the amount you may be billed. |
Rule of thumb: amounts coded PR (Patient Responsibility) may be yours to pay. Amounts coded CO or PI are between your provider and your insurer — you generally do not owe them.
EOB terms in plain English
The words on an EOB that confuse people most — explained simply.
Deductible
The amount you pay out of pocket each year before your plan starts sharing costs. Shows up as PR-1.
You may owe thisCopay
A fixed amount you pay for a visit or service (for example, $30 for a primary-care visit). Shows up as PR-3.
You may owe thisCoinsurance
Your percentage share (for example, 20%) of the allowed amount after you’ve met your deductible. Shows up as PR-2.
You may owe thisAllowed amount
The maximum your insurer will pay for a service under its contract with the provider. Your share is calculated from this number, not the billed charge.
Amount billed
The provider’s full charge before any insurance discount. It is almost never what you actually owe.
Plan discount / adjustment
The difference between the billed charge and the allowed amount — written off by an in-network provider. Shows up as CO-45.
Not your billPatient responsibility
The total your plan assigns to you across deductible, copay, and coinsurance. This is what your provider will bill you for.
You may owe thisOut-of-pocket maximum
The most you’ll pay in a year for covered, in-network care. After you hit it, your plan pays 100% of covered services.
EOB vs. bill
An EOB is your insurer’s summary of a claim. Your bill comes separately from the provider. Always compare the two before paying.
Common questions about your EOB
No. An EOB (Explanation of Benefits) is a summary your health insurer sends after a claim, showing what was billed, what the plan allowed, what it paid, and what you may owe. Your actual bill comes separately from your provider. Don’t pay from the EOB alone — wait for the provider’s bill and confirm it matches.
Most plans share costs with you through a deductible (an amount you pay before the plan starts sharing), a copay (a fixed fee per visit), and coinsurance (a percentage of the cost after your deductible). Amounts marked with a PR (Patient Responsibility) code on your EOB are the parts your plan assigns to you.
A copay is a fixed amount you pay for a visit (for example $30). A deductible is the total you pay out of pocket each year before your plan begins sharing costs. Coinsurance is your percentage share (for example 20%) of the allowed amount after you’ve met your deductible.
The allowed amount is the maximum your insurer will pay for a service under its contract with the provider. The difference between what the provider billed and the allowed amount appears as a CO-45 adjustment — your in-network provider writes that off, so you do not owe it.
You may not have met your annual deductible yet, the visit may include coinsurance, or some services may not be covered. Look at the lines marked with PR codes — those are the amounts your plan assigns to you. Anything marked CO or PI is generally not your responsibility.
Not yet. Wait for the actual bill from your provider, then confirm the amount matches the patient-responsibility (PR) total on your EOB before paying. If a bill includes amounts marked CO (like a CO-45 provider discount), question it before paying.
Work in billing or coding?
This tool explains EOBs for patients. If you’re on the provider side, the Denial Code Decoder covers the full CARC & RARC set with causes, fixes, and ready-to-send appeal letters. Medmio builds AI tools that help practices code and bill accurately the first time.