EOB mismatch / balance billing

Billed more than the insurer's own EOB says you owe

After an in-network outpatient procedure, the insurer's Explanation of Benefits lists the patient's responsibility at one amount. The hospital's bill, for the same service, charges more.

Illustrative example built from BillMender's rules engine — not a real patient's bill, and not a claim about any specific hospital.

The bill

Outpatient procedure — patient balance per hospital bill$420.00

Bill exceeds EOB patient responsibility$300.00

The insurer's EOB assigned $120 as the patient's responsibility for this service. The hospital, which is in-network and contractually bound to accept the negotiated rate, billed $420 instead — a $300 gap with no explanation.

Basis: ERISA § 503 right to claim review (29 CFR § 2560.503-1); state insurance code on balance billing.

Why this happens

Hospital billing systems and insurer claims systems don’t always sync on the final adjudicated amount, especially after a claim correction — the bill goes out before the EOB catches up, and nobody circles back to fix it unless the patient asks.

BillMender is a document-preparation tool, not a law firm, and does not provide legal advice. We don't guarantee any outcome or dollar amount. Estimates are based on public reference pricing, not your hospital's actual contract rates.