How to Read an Explanation of Benefits Before You Pay a Bill

An Explanation of Benefits, or EOB, is the statement your health plan sends after it processes a claim. It shows what the provider charged, what your plan allowed and paid, and what you may still owe. It is not a bill. Read it first, then pay the provider only when the bill matches the amount the EOB says is yours.

The order matters because a bill can arrive before your plan has paid, or with mistakes the EOB would expose. The Centers for Medicare & Medicaid Services (CMS), the federal agency that runs Medicare, gives a simple test: the provider's bill should never be more than the patient balance on the EOB. If it is more, contact the provider before paying.

This guide covers job-based, Marketplace, Medicare Advantage and Part D plans. Original Medicare's version, the Medicare Summary Notice, is covered below.

Key takeaways

An EOB explains how your plan handled a claim. It is not a bill, and you do not pay from it.
Four numbers matter most: what the provider charged, the allowed amount, what the plan paid and what you owe.
With an in-network provider, the gap between the charge and the allowed amount is a discount, not a debt.
Pay a provider's bill only once it matches the "what you owe" line, minus anything you already paid at the visit.
A denied claim on an EOB can be appealed. Job-based and Marketplace plans generally give you 180 days from the denial notice to file an internal appeal. Medicare has its own deadlines.
Adding up this year's EOBs gives you a real number to use when you compare 2027 plans during open enrollment.

What an EOB is and when you get one

Each time a doctor, lab or hospital sends your plan a claim, the plan decides how much to pay and records the result on an EOB. You may get it by mail, through your plan's website or app, or both. CMS notes that the EOB should normally reach you before the provider's bill, apart from a copay or coinsurance the office may collect at the visit. If a bill arrives and you never saw an EOB for that visit, call your plan and confirm the claim was filed.

Medicare uses two kinds of statement:

Original Medicare sends a Medicare Summary Notice by mail. It shows each Part A or Part B service billed to Medicare, the amount Medicare paid and the most you could owe the provider. You can also see claims in your online Medicare account, usually within 24 hours after Medicare processes them.
Medicare Advantage, Part D and other health or drug plans send an EOB for each month in which you fill a prescription, see a provider or file a claim.

The EOB, field by field

Layouts vary by insurer, but CMS describes the fields most EOBs share.

Field	What it means	What to check
Claim number	The plan's reference number for this claim	Keep it handy for any call to the plan or the provider
Date of service	The day you received care	It matches a day you actually had care
Provider and service description	Who treated you and the type of care, such as an office visit, lab test or screening	You recognize both the provider and the service
Provider charges	The amount the provider billed	This is the list price, not your price
Allowed charges	The amount the provider will be paid under your plan, which may be lower than the charge	Your share is calculated from this figure
Paid by insurer	What your plan paid the provider	A zero can mean the cost went to your deductible, or that the claim was denied
What you owe, or patient balance	Your share after the plan pays	The most the provider's bill should show for this service
Remark codes	Short codes, usually two or three characters, explaining a charge or payment, with a key at the bottom of the EOB	Read every code beside a reduced or denied line

How your share is broken down

Your EOB may split the patient balance into the pieces that produced it: the part that went toward your deductible (the amount you pay each year before the plan starts sharing costs), a copay (a flat fee), coinsurance (a percentage of the allowed amount), and anything the plan did not cover. If those terms are new, the guide to premiums, deductibles, copays and coinsurance explains each one with examples.

CMS points out that the patient balance does not show money you already paid, such as a copay at the front desk, so subtract that yourself before comparing it with the bill.

Why the allowed amount is lower than the charge

The allowed amount, also called an eligible expense, payment allowance or negotiated rate, is the most your plan will pay for a covered service. An in-network provider subtracts anything it charged above that as an adjustment, because it agreed to the lower price with your plan. An out-of-network provider has no such agreement and may bill you the difference, a practice called balance billing. Federal law blocks that for emergency care and a few other situations, covered in the guide to what the No Surprises Act protects you from.

A worked example

Example: In 2026, Dana has an MRI at an in-network imaging center. Her plan has a $2,000 deductible and 20% coinsurance after the deductible, and she has already paid $1,400 toward the deductible this year. All of these numbers are illustrative.

The EOB lists provider charges of $1,800 and an allowed amount of $900. Dana has $600 of deductible left ($2,000 minus $1,400), so she pays the first $600 of the allowed amount in full. Coinsurance applies to the remaining $300: 20% of $300 is $60. Her patient balance is $600 plus $60, or $660. The plan pays the rest of the allowed amount: $900 minus $660, or $240. The other $900, the gap between the $1,800 charge and the $900 allowed amount, is a network discount she never owes.

Before the EOB reaches her, the imaging center sends a statement for $1,800 because it has not yet posted the plan's payment and the discount. Dana waits for the EOB, then calls the imaging center with the claim number and asks for a corrected bill of $660.

How to match an EOB to a provider's bill

Line up the basics. The date of service, the provider's name and the service description should be the same on both documents.
Compare the amounts. Take the EOB's patient balance, subtract anything you paid at the visit, and compare the result with the bill's balance due. If the bill is higher, call the provider before paying.
Look for the plan's payment. A bill that shows the full charge with no insurance payment or adjustment may mean the provider has not yet posted your plan's payment, or that no claim reached the plan. The claim number on the EOB lets the billing office check.
Ask for an itemized bill. CMS suggests asking the billing office to break the bill down into the cost of each item and service.
Check it against your medical records. According to CMS, nothing should appear on a bill unless your records document it. Some providers charge for copies of records, so ask about any fee first.

Errors and red flags to look for

A visit, test or supply you did not receive.
The same service listed twice. CMS notes that double billing is especially common when more than one provider treated you, so check each provider's bill.
A wrong date of service, or a provider you do not recognize.
An in-network provider processed as out-of-network, which can show up as a smaller plan payment and a larger share for you.
A denial for a reason you can fix, such as missing information from the provider.
Billing codes that do not describe your care. CMS suggests searching each code together with the words "medical billing code" and comparing the description with what happened.
An out-of-network bill for emergency care, or for care during a visit to an in-network hospital or surgery center, where the No Surprises Act generally limits you to in-network cost sharing.

What to do when something looks wrong

A billing mistake

Call the provider's billing office with the claim number and your EOB in front of you. Your plan can also help: CMS notes that an insurer may be able to get billing errors fixed with the provider. Write down who you spoke with, the date and any reference number.

A denied or reduced claim

If the EOB shows a denial and the remark code does not explain it, ask your plan for the reason in writing. With a job-based or Marketplace plan, you generally have 180 days (6 months) from the denial notice to file an internal appeal; some job-based plans allow longer, so check your plan documents. The plan then has 30 days to decide an appeal for care you have not received yet and 60 days for care you already received. Medicare runs a separate appeal process with different deadlines, so follow the instructions on your Medicare plan's denial notice or, with Original Medicare, on your Medicare Summary Notice. The guide to appealing a denied health insurance claim covers the steps.

A bill that breaks surprise-billing rules

Call the federal No Surprises Help Desk at 1-800-985-3059 or file a complaint online through CMS. Have the bill, your insurance card and the EOB ready.

If the bill is correct but more than you can pay, the guide to lowering a medical bill covers hospital financial assistance, discounts and payment plans.

Use this year's EOBs to choose next year's plan

Your EOBs are a record of what your care actually cost you. Before you compare plans for 2027, add up the patient balances from your 2026 EOBs and list the providers and drugs you used. On HealthCare.gov, open enrollment for 2027 coverage runs from November 1, 2026 to January 15, 2027. Enroll by December 15, 2026 and pay your first premium for coverage that starts January 1, 2027. The guide to comparing health plans by total yearly cost shows how to turn that total into a side-by-side comparison.

The out-of-pocket maximum sets your worst case for covered in-network care. For most job-based and Marketplace plans, the federal ceiling on yearly in-network out-of-pocket costs is $10,600 for one person and $21,200 for a family in 2026. For plan years that start in 2027, it rises to $12,000 and $24,000. A plan's own maximum can be lower, so check the plan's documents. If your 2026 EOBs show you reached your plan's maximum, compare 2027 plans by yearly premiums plus the out-of-pocket maximum, because that sum is roughly what a similar year of covered in-network care would cost you.

Frequently asked questions

Is an Explanation of Benefits a bill?

No. An EOB shows how your plan processed a claim and what you may owe. The bill comes separately from the provider. Pay the provider, not the plan, and only once the bill matches the EOB's patient balance.

Why is the allowed amount so much lower than what the provider charged?

The allowed amount is the most your plan will pay for that service. An in-network provider writes off the difference. The amount that counts toward your deductible, and any coinsurance percentage, is figured from the allowed amount, not the charge; a copay is a flat fee either way.

What if the EOB says you owe $0 but the provider sends a bill?

Do not pay it yet. Call the provider's billing office with your claim number. The bill may have been sent before the plan's payment was posted, or it may be an error. Under CMS's test, a bill should not be more than the EOB's patient balance.

What if you never received an EOB?

Check your plan's website or app, then call the plan to confirm the claim was filed. If you have Original Medicare, look for a Medicare Summary Notice instead, or check your online Medicare account.

Sources

How to read a health insurance explanation of benefits (CMS)
How to read your medical bill (CMS)
Check your medical bill for errors (CMS)
Know your medical bill rights when using insurance (CMS)
Checking the status of a claim (Medicare.gov)
Internal appeals (HealthCare.gov)
When can you get health insurance? (dates and deadlines) (HealthCare.gov)
Premium Adjustment Percentage, Maximum Annual Limitation on Cost Sharing, Reduced Maximum Annual Limitation on Cost Sharing, and Required Contribution Percentage for the 2027 Benefit Year (CMS, January 29, 2026)