Explanation of benefits (EOB)

An explanation of benefits (EOB) is your health plan’s written record of one processed claim: what was charged, what the plan paid, and what is left for you. Plans and billing offices call it the EOB. It is not a bill and asks you for nothing; the bill comes separately, from the provider, and the EOB is what you check it against.

For each service, it shows these lines:

The part people get wrong is which line to read. The charge is the wrong one: 20% coinsurance means 20% of the allowed amount, never 20% of what was billed. Patient responsibility is the line to hold a bill against, and from an in-network provider the bill should match it. One visit can also produce several claims, since the facility and the physician group bill separately, so match each bill to its own EOB instead of adding them up.

A denied line is where an appeal starts. The EOB states the plan’s reason as shorthand, a code or a one-line note. That tells you what kind of problem you have, but an appeal needs the denial in writing: the specific reason, the criteria applied and the deadline for your next step. Some denials need no appeal. An emergency claim denied for lack of prior approval calls for reprocessing, since emergency care cannot be pre-approved.

The EOB comes from your plan after it processes a claim, often weeks before the provider’s bill catches up. Match it to the bill by date of service and provider name, then read patient responsibility and any denied line. Check it against your own memory too: a service you never received, or one listed twice, is worth questioning in writing.

In New York: the patient responsibility line is the number to hold a provider to, and state law backs it where you had no choice. After emergency care, after an out-of-network clinician treated you inside a participating facility, and after a ground ambulance ride, which federal law leaves out, New York limits you to in-network cost sharing; if a bill runs past that line, the provider and the plan settle the difference through independent dispute resolution at the Department of Financial Services. When the EOB shows a denial instead, the order is fixed: the plan’s internal appeal first, then New York’s external appeal, decided through DFS by a reviewer who does not work for your plan. Both routes depend on plan type. A self-funded employer plan is federally regulated, so New York’s external appeal and surprise billing framework do not reach it, and complaints go to the US Department of Labor, 866-444-3272, rather than DFS, 800-342-3736. One question to HR settles which you have: “Is our health plan fully insured or self-funded?” Last, keep every EOB for the year. If your out-of-pocket medical costs over twelve months exceed 10% of gross income, New York’s hospital financial assistance law treats you as underinsured, and its income tiers then apply to your share of a hospital bill. The EOBs are your evidence.

What to do:

• Match before you pay. If a bill asks for more than patient responsibility, write to the provider, quote the EOB figure and ask for a corrected balance.
• Get any denial in writing, then file the plan’s internal appeal. How appeals work.
• Tell billing about the appeal and ask, in writing, for the account to be held while it runs.
• Out-of-network clinician at an in-network hospital? That is a surprise bill, not an appeal: ask the plan to reprocess it at in-network cost sharing.

Also called: EOB. Full guide: How to read and dispute a medical bill. Reference: Explanation of benefits (EOB) on Wikipedia — general definition, not New York specifics.