An explanation of benefits is a notice from your health plan showing what a provider charged, what the plan allowed, what the plan paid and what is left as your responsibility. The Centers for Medicare and Medicaid Services states it plainly: "An explanation of benefits isn't a bill." Reading one means reading four numbers across a single service line and one short code that explains why those numbers came out the way they did.
This article explains what the fields on a US explanation of benefits mean. It is general information, not medical, insurance, legal or financial advice. It does not interpret any individual document, does not say whether an amount is owed, and does not tell anyone whether to pay, appeal or dispute anything. Your plan documents govern your coverage. This site's full position is set out on its disclaimer page.
Sources read September 8, 2026. Layouts differ by plan and change over time, so field names on your notice may not match the ones below word for word.
What the document is, and what it is not
An explanation of benefits is the plan's receipt for a claim. CMS describes it as a notice that "shows you the total charges for your visit" and one that "helps you understand how much your health plan covers, and what you'll pay when you get a bill from your provider."
Two consequences follow, and both are the reason this document confuses people.
The first is that the money on it has usually not been requested from you yet. The provider bills the plan, the plan processes the claim, the plan tells you what it did, and only then does the provider bill you for the remainder. Two documents, two senders, two arrival dates.
The second is subtler and CMS states it in one clause: the patient balance "only shows what you owe, not if you've already paid for it." A copayment handed over at the front desk does not necessarily show as paid here. That single sentence is where a large share of "I am being billed twice" panic comes from, and it is on CMS's own consumer page rather than in any plan's fine print.
The field-by-field walkthrough
CMS's consumer guide to reading a health insurance explanation of benefits, last modified August 25, 2026 and read September 8, 2026, defines the fields consumers ask about. Its definitions are short enough to quote in full, and they are the most neutral set available, because CMS is not a party to your claim.
| Field on the notice | CMS's definition | What it is really telling you |
|---|---|---|
| Provider charges | "the amount your provider bills for your visit" | A list price, before any contract is applied |
| Allowed charges | "the amount your provider will be paid. This may not be the same as the Provider Charges" | The figure every later calculation runs on |
| Paid by insurer | "the amount your health plan will pay to your provider" | The plan's share of the allowed figure |
| What you owe, or patient balance | "the amount you owe after your insurer has paid everything else" | Your share, before the provider's own records are applied |
| Claim number | "a reference number" | The identifier to quote in every call about this service |
| Payee | "the person who gets reimbursed for any overpayments" | Who receives money back if too much was paid |
| Remark code | "a note from the health plan that explains more about the costs, charges, and paid amounts for your visit. The code is usually 2 or 3 letters and numbers" | The reason field, and the most skipped part of the page |
Read across one service line, in that order, and the arithmetic tells its own story: what was asked, what was recognized, what was paid, what is left.
The gap between charges and allowed charges
The largest number on the page is usually the least meaningful one.
CMS's definition of allowed charges carries its own warning: "This may not be the same as the Provider Charges." The difference between the two exists because contracted providers agree in advance to accept a negotiated figure, so the list price is a starting point rather than a price anyone expects to collect.
That gap behaves completely differently depending on whether the provider is contracted with your plan, and it is the single most consequential thing on the document. Our explainer on in-network and out-of-network allowed amounts sets out why the same phrase describes an agreed price in one case and a plan-set benchmark in the other.
For reading purposes the rule is short: your cost share is calculated from the allowed figure, not from the charge. A reader who compares their share against the charge will conclude the plan paid almost nothing, and a reader who compares it against the allowed figure will see what actually happened.
How your share was calculated
The patient balance is not a single kind of money. It is whatever remains after the plan applied the terms of your coverage, and those terms have names.
A fixed amount attached to a visit type is a copayment. A percentage of the allowed figure is coinsurance. An amount you pay in full because the plan's cost sharing has not started yet is the deductible. Which of the three produced the number on your notice is usually visible in the columns or in the remark code.
The difference matters, because the three behave differently across a year. The distinction between the two cost-share shapes is set out in our comparison of copay and coinsurance.
The order a plan applies them in is the other half of the arithmetic, and it is covered in our guide to how a deductible and coinsurance work.
There is also a category that is not cost sharing at all: amounts for services the plan did not cover, or amounts above what the plan recognized. Those sit in the same column and behave differently, which is the subject of the next section.
The remark code is the reason field
Every explanation of benefits carries short codes that most readers scroll past. CMS calls the remark code "a note from the health plan that explains more about the costs, charges, and paid amounts for your visit," and notes the code "is usually 2 or 3 letters and numbers."
This is the field that answers why. Why a service was reduced, why part of a charge was not recognized, why a line paid at a different rate than the one next to it, and, when a claim was denied, on what stated ground. The code is expanded in a legend, usually on the reverse or on a later page of the same notice, and the plan's member services can explain a code that the legend leaves ambiguous.
If a notice is going to be discussed with anyone, the two things worth having in front of you are the claim number and the remark codes for the lines in question. Everything else on the page can be reconstructed from the plan's own record; the code is the part that explains the decision.
Reading the notice against the bill that follows
The explanation of benefits is most useful as a comparison document.
CMS's guide to reading a medical bill, last modified August 25, 2026 and read September 8, 2026, gives the instruction in one line: "When you get a bill from your provider or facility, compare it with the Explanation of Benefits to make sure you were billed" correctly. The same guide lists what to check on the bill itself, including the dates of service, which it says to confirm you "got services on the date(s) listed," and the description of services or supplies, which should match what was received.
Three comparisons do most of the work: the dates of service on both documents, the patient responsibility figure on the notice against the balance due on the bill, and any payment you already made against the payments shown. Where the two documents disagree, the discrepancy itself is the question to raise, with the claim number and the provider's account number both in hand.
What accumulates, and what does not
Many notices show running totals for the deductible and the out-of-pocket maximum. Those totals are the part of the document that describes your year rather than your visit.
What they include is plan-specific and narrower than people expect. Amounts for non-covered services generally do not accumulate, and amounts billed above what the plan recognized are frequently not cost sharing at all. The general mechanics of which amounts move those ceilings are in our explainer on what counts toward your out-of-pocket maximum, and the plan document is the authority for your own plan.
If the totals on a notice do not match your own tally, the plan's member services can say which amounts posted to which accumulator, quoting the claim number.
Where to take a question this article cannot answer
Your plan's member services, for how a claim was processed, what a remark code means and which accumulator an amount posted to. Your plan administrator or benefits contact, for what your plan document says. The provider's billing office, for the charge, the codes billed and payments already recorded. Your state Department of Insurance, for a complaint about a plan's conduct; the National Association of Insurance Commissioners maintains the directory of state insurance departments, read September 8, 2026. HealthCare.gov, read the same day, sets out the general shape of internal appeals and external review if a claim decision is being contested, and the federal No Surprises Help Desk takes questions about billing protections at 1-800-985-3059. Anything clinical belongs with your clinician.
Frequently asked questions
Is an explanation of benefits a bill?
No. CMS states that "an explanation of benefits isn't a bill." It is the plan's record of how a claim was processed. Any amount actually requested from you arrives separately, from the provider or facility.
What is the difference between provider charges and allowed charges?
CMS defines provider charges as "the amount your provider bills for your visit" and allowed charges as "the amount your provider will be paid," adding that the two "may not be the same." Cost sharing is calculated from the allowed figure.
Why does my EOB say I owe money I already paid?
CMS notes that the patient balance field "only shows what you owe, not if you've already paid for it." A copayment collected at the visit may not appear as paid on the notice. The provider's own statement is where payments already made are recorded.
What is a remark code on an explanation of benefits?
CMS describes it as "a note from the health plan that explains more about the costs, charges, and paid amounts for your visit," usually two or three letters and numbers. It is the field that gives the plan's stated reason, and the legend on the notice expands it.
What should I do if the EOB and the provider's bill do not match?
CMS's guidance is to compare the two documents when the bill arrives, and its consumer pages direct questions about a bill to the provider's billing department and questions about claim processing to the plan. Keeping the claim number, the account number and the date of any call is what makes a follow-up straightforward.
Sources, all read September 8, 2026: Centers for Medicare and Medicaid Services, "How to read a health insurance explanation of benefits," page last modified August 25, 2026. CMS, "How to read your medical bill," last modified August 25, 2026. CMS, "Check your medical bill for errors," last modified August 25, 2026. HealthCare.gov, "How to appeal an insurance company decision," no date shown. National Association of Insurance Commissioners, state insurance department directory. No dollar amount, error rate or claim outcome is asserted in this article. Field names and layouts vary by plan; your notice and your plan document govern.
