You know when you get a letter from your health insurer that looks like a bill, but isn’t? (It might even say “THIS IS NOT A BILL” at the top.) That is an explanation of benefits, also known as an EOB.

An EOB is simply a record, from your health insurer, of how your healthcare claim was processed. You can compare it to the bill you receive for the same claim from a hospital, clinic, or other healthcare provider. If anything looks different, you should call the member services number on your insurance card and let them know. UMR’s Healthy You magazine put together a short explainer on EOBs, which you can read online here or download here as a PDF.