Your hospital bill doesn't match your EOB — what that means

Your insurer’s Explanation of Benefits says you owe $312. The hospital’s bill says $1,847. Both arrived the same week, both look official, and nobody sent an explanation for the gap.

This is one of the most common things people write to us about, and it is worth slowing down on. A mismatch is not proof that anyone did anything wrong — there are boring explanations that turn out to be correct. But it is also the single place where real billing errors surface most often, because the EOB and the bill are two independent accounts of the same visit.

Here is how to work out which explanation applies to you.

First, make sure you are comparing the right two numbers

Most “mismatches” are actually a comparison of two different things. On the EOB, find the line usually called patient responsibility — it may also read “you may owe,” “your share,” or “amount not covered.” That is the only EOB number the provider’s bill should agree with.

It is not the amount billed, and it is not the allowed amount. Those are both larger, and comparing either one to your bill will look alarming when nothing is wrong.

If patient responsibility and the bill now agree, you are done — the bill is consistent with what your plan decided, and any argument you have is with the plan, not the provider.

If they still disagree, work through these five causes

1. The bill was printed before the claim finished. Providers often bill on their own schedule. If the bill is dated before the EOB, it may simply predate your insurance being applied. This is the most common answer, and it resolves itself — ask for a re-issued statement reflecting the processed claim.
2. The claim was never submitted to your insurer. Check whether the EOB covers the same date of service and the same provider as the bill. A missing claim looks identical to an overcharge from where you are sitting.
3. Part of the visit was out of network. The hospital can be in network while the radiologist, anesthesiologist or pathologist who read your results is not. That is exactly the scenario the No Surprises Act was written for — see the section below.
4. Different services were coded than were billed to you. This is where an itemized bill matters. A summary statement showing one total cannot be checked against anything; a line-by-line bill can.
5. You are being balance billed. The provider is charging you the difference between what they asked for and what your plan allowed. In some situations that is permitted; in others it is prohibited.

When the difference may not be legal at all

The federal No Surprises Act limits what you can be charged in specific situations — broadly, emergency care, and care from an out-of-network provider at an in-network facility. In those circumstances you generally cannot be billed more than your in-network cost sharing, and the provider is expected to settle the rest with your plan rather than with you.

What to do next, in order

1. Request an itemized bill in writing. You are asking for every line, with its billing code and charge — not a summary. Without it, nobody can tell you whether the total is right.
2. Put the itemized bill beside the EOB and check service dates, the provider name, and patient responsibility.
3. Call your insurer first, not the provider. The insurer decided the amount; the provider is collecting it. Ask them to explain the difference on the record.
4. Ask the provider’s billing office to hold the account while the discrepancy is reviewed, so it does not age toward collections while you wait.

What to say when you call

Write down who you spoke to and when. If the matter goes further, that record is the difference between an argument and a case.

Where Mareva fits

You can do every step above yourself with nothing but the two documents and a phone. If it would help to have the comparison done for you, Mareva reads a bill and an EOB together, explains each line in plain language — in any of ten languages — flags the amounts worth questioning, and drafts the letter for you to review and send in your own name. The first scan of any document is free.