Short answer: An Explanation of Benefits (EOB) is not a bill: it shows what your provider charged, what your plan allowed and paid, and what you may owe. If a claim or prior authorization is denied, you have the right to an internal appeal with the plan and then an independent external review.
After you get care, the provider sends a claim to your plan. Once it’s processed, you receive an Explanation of Benefits (EOB). The most important thing to know: an EOB is not a bill. It’s a summary that typically shows the billed amount, the plan’s allowed amount, what the plan paid, any discount, and the portion you may owe (deductible, copay, or coinsurance). Compare it to the bill the provider sends to make sure they match.
Plans pay for services that are medically necessary under the plan’s terms. When a claim or a prior authorization is denied, you have appeal rights:
- Internal appeal: you ask the plan to reconsider. The denial notice explains the reason and the deadline (often 180 days to file).
- External review: if the internal appeal fails, the ACA gives you the right to an independent external review by a reviewer not affiliated with the plan, whose decision the plan must follow.
For urgent situations, expedited timelines apply. Keep copies of EOBs, denial letters, and any medical records or letters of medical necessity from your provider; documentation is what wins appeals.
Sources
- ACA internal claims, appeals, and external review: 45 CFR §147.136; ERISA claims procedure 29 CFR §2560.503-1.
- Employee Benefits KB (Coverage Mechanics, claims/EOB and appeals).
Content history
Originally published: June 16, 2026
Last reviewed: June 16, 2026