How do I read an EOB and compare it with a medical bill?

An explanation of benefits, or EOB, explains how your health plan processed a claim. It is not a bill. Match it to the provider's bill, check the service and claim details, then reconcile the patient share with payments you already made. If the figures disagree, identify whether the unresolved question belongs with the provider's billing office, the health plan or both.

Start with the documents, not the largest number. The amount a provider charged, the amount the plan recognized and the amount still unpaid by you can be three very different figures.

Match the person, service and claim

Put the EOB, provider bill and relevant receipts together. Check the patient, provider, date of service, service description and claim number. The date a statement was printed is not necessarily the date care occurred.

The CMS guide to reading an EOB identifies those claim details and the difference between the insurer's explanation and a provider's payment request. Use the claim reference when asking a question, rather than asking someone to find “that bill from last month.”

One episode of care can involve different providers. Do not combine two statements merely because they share a date. Conversely, two copies of the same claim explanation do not establish two separate debts. Track the actual provider and service lines.

If a service is unfamiliar, ask for an understandable description and an itemized bill. Do not guess a diagnosis or change billing codes yourself to make the numbers work. If you believe the service did not occur, raise that specific issue through the relevant established channels.

Separate the charge from the allowed amount

The EOB can show the provider's original charge, an allowed amount, the health plan's share and your assigned responsibility. Read the labels and explanatory notes on your own document; different layouts do not always use identical words.

An allowed amount is not automatically the amount the insurer pays. Part of it may be assigned to you under the applicable coverage. Nor should the difference between a provider's charge and an allowed amount automatically be added to your bill. Its treatment depends on the actual service, network arrangement and applicable protections.

The worked example below supplies that treatment explicitly: a covered, in-network service with an agreed adjustment that the provider does not collect from the patient. It does not decide an out-of-network bill, an uncovered service, a surprise-billing dispute or what any particular provider may legally charge.

Work through a complete original claim

A fictional provider submits a $1,200 charge. Under the supplied plan and provider arrangement, the allowed amount is $800 and the remaining $400 is a contractual adjustment, not patient debt.

At processing, the patient has $300 of the applicable deductible remaining. The plan assigns that first $300 of the allowed amount to the patient. The remaining allowed amount is $500.

The supplied terms then assign 20% of that $500 to the patient as coinsurance: $100. The insurer pays the other $400. There are no copayments, other charges, secondary coverage or out-of-pocket-limit adjustments in this case.

The patient's total assigned share is $400: $300 deductible plus $100 coinsurance. The $800 allowed amount is fully accounted for by $400 from the insurer and $400 from the patient.

HealthCare.gov's deductible explanation distinguishes the deductible from the copayments or coinsurance that can follow it, and notes that actual services can have different rules. The calculation here follows the supplied fictional rules; it is not a template for every service.

Scroll horizontally if needed. The original fictional claim has one covered service and no additional adjustment beyond those listed.

Twenty percent of the full $1,200 would be $240. Adding that to the $300 deductible would give $540, overstating the supplied patient share by $140. That mistake uses the wrong base and ignores the order of the calculation.

Subtract the payment already made

Suppose the patient paid $125 to this provider at the visit, with a receipt assigning it to this exact service. The total assigned patient share remains $400, but the unpaid amount is $275: $400 less the credited $125.

CMS notes that an EOB's patient balance may not reflect money you have already paid. That is why the provider's payment ledger and your receipt matter alongside the insurer's explanation.

In the fictional case, a provider statement incorrectly requests $675. Its lines show $400 assigned patient share, plus the $400 contractual adjustment, less the $125 already paid. The arithmetic reaches $675, but the added adjustment contradicts the supplied arrangement.

The supported correction is to remove that $400 from the requested amount, leaving $275. An account can add up perfectly while including the wrong charge. Showing the offending line is more useful than telling the billing office that its total “seems too high.”

If instead the provider requested the full $400 share because the $125 receipt had not been credited, that would be a different error. The remaining balance would still be $275, but the required repair would be the missing payment credit. Preserve the cause as well as the corrected total.

Check whether a new EOB replaces the old one

A later explanation may reflect reprocessing of the same claim. Compare the claim reference, service lines, processing dates and status rather than adding every document together. Ask the plan how the versions relate if that is unclear.

In a separate fictional branch, the plan corrects the deductible information used for this same service. Only $200, not $300, remained when the claim was processed. All other terms stay unchanged.

The $800 allowed amount now has $200 assigned to the deductible and $600 left. Twenty percent of $600 is $120. The revised patient share is $320, and the insurer's share is $480.

The patient share has fallen by $80, from $400 to $320. The insurer's share has risen by the same $80. The revised explanation replaces the earlier allocation for this claim; it does not create another $320 obligation beside the original $400.

If only the original $125 has been paid, the revised unpaid amount is $195: $320 less $125. Adding the two EOB patient shares to get $720 would count the same claim under two processing states.

Follow an overpayment through to the end

Now change the payment timing. Suppose the patient paid the original remaining $275 before the corrected EOB arrived. Including the earlier $125, total patient payments to this provider are $400.

Against the revised $320 patient responsibility, that leaves an $80 overpayment. The right question is how the provider will handle that credit under the actual circumstances. It is not another bill for $195, because that figure assumes the later $275 payment never happened.

Keep the corrected explanation, both receipts and a provider ledger showing where the credit sits. If the provider agrees to a refund, record its actual amount and completion. A promised refund or account credit is not money already returned to your bank.

This example assumes the plan and provider have completed the stated correction and recognize the revised allocation. An actual disagreement remains unresolved until the relevant parties clarify it. Do not infer a final credit solely from a document you have not matched to the provider's account.

Send the right question to the right party

Ask the provider's billing office about itemization, service descriptions, a payment missing from its ledger or a bill inconsistent with the processed allocation. Ask the health plan about its coverage decision, deductible application, payment calculation or explanation codes. Some issues require both records to be corrected.

An effective question is specific: “For this claim and service date, the current EOB assigns $400 to me. My receipt shows $125 paid. Your statement requests $400 without a payment credit. Can you trace that receipt and issue an updated statement?” This is an illustrative question, not correspondence sent for a real patient.

Read remark codes and any denial explanation. A request for missing information, a coverage exclusion and a duplicate-claim adjustment are different findings. Do not assume every zero insurer payment means you owe the full submitted charge.

If you disagree with an insurance decision, use the actual plan's correction or appeal process and applicable deadlines. A routine phone question should not be assumed to preserve a formal appeal right. Obtain the relevant instructions promptly when a decision needs review.

Keep the billing clock visible

Record the bill's due date, the issue raised and any response or payment arrangement actually agreed. Ask how the provider will handle the account while the identified question is reviewed. Do not assume an inquiry automatically pauses billing or collections.

If the bill is accurate but unaffordable, that is a different conversation from a calculation error. Ask the provider about available assistance or payment arrangements and their actual conditions. Do not erase a valid amount in the worksheet simply because it cannot be paid immediately.

Keep medical and billing information private. Use verified contact details from established plan or provider sources, and share the relevant documents through an appropriate route. A public screenshot containing identifiers is unnecessary for asking a general billing question.

Close the record with one current balance

1. Match the patient, provider, service and claim.
2. Identify the current processing version and read the explanation notes.
3. Reconcile submitted charges, adjustments, allowed amounts and assigned shares.
4. Credit payments already made to the same provider and service.
5. Raise a specific unresolved line with the responsible party.
6. Track applicable due dates, correction steps and appeal instructions.
7. Verify the corrected bill, completed payment or actual refund.

The statement-and-current-balance guide illustrates why dated records can show different amounts without referring to different debts. Here, the additional task is to connect the health plan's claim processing with the provider's ledger. Matching totals alone is not enough if they describe different services or versions.