Notes on payer behavior

Medicare denied the claim: the appeal levels, deadlines, and the one denial you can't appeal

Clearia · September 2026 · Medicare, appeals

Medicare's appeal process is the most rule-bound in medicine and the most predictable, which makes it the easiest to win when you follow it and the easiest to lose when you don't. Five levels, fixed deadlines at each, and one class of denial that isn't appealable at all. Here's the map for a Part B claim.

The five levels

1. Redetermination by the Medicare Administrative Contractor. Request within 120 days of the initial determination (the remittance date, plus a five-day mailing presumption). The MAC decides within 60 days. No minimum dollar amount.
2. Reconsideration by a Qualified Independent Contractor. Request within 180 days of the redetermination notice. The QIC decides within 60 days. Submit all evidence here; new evidence at later levels needs good cause.
3. Administrative Law Judge hearing. Request within 60 days of the reconsideration notice. A minimum amount in controversy applies, updated each year by CMS, and claims can be aggregated to reach it.
4. Medicare Appeals Council review. Within 60 days of the ALJ decision.
5. Federal district court. Within 60 days of the Council decision, with a higher amount-in-controversy threshold.

For an independent practice the game is levels one and two. Most administrative denials reverse at redetermination when the file is complete. Levels three and up are for high-dollar patterns, aggregated.

The denial you can't appeal

A timely-filing denial (CO-29) on a Medicare claim is not an initial determination, and the appeal process doesn't apply. Filing a redetermination on one goes nowhere. The route that exists is a reopening under the exceptions Medicare recognizes: contractor error, retroactive Medicare entitlement, and a few others. Knowing which door to use is the whole game on these. The Medicare timely-filing exception in detail.

Reopenings versus appeals

Separate from the appeal ladder, a contractor can reopen a determination: within one year for any reason, within four years for good cause, and at any time for fraud or clerical error. A reopening is the right tool for a clerical fix (a transposed digit, a wrong modifier) and the wrong tool for a substantive dispute. Ask for the reopening explicitly; a corrected claim that looks like a duplicate gets denied as one.

What wins at redetermination

• The claim data corrected, with the correction explained in one sentence.
• The documentation the denial names. For a CO-50, the note and the LCD's covered diagnosis. For a CO-97 or CO-236, the modifier and the procedure note. For a CO-4, the modifier fix.
• The redetermination form or a letter with all required elements: beneficiary name, Medicare number, service and date, the item you disagree with, and a signature.

Medicare's remittance carries the reason and remark codes like any other 835. The denial codes table sorts them.

Medicare Advantage is different

A Medicare Advantage plan runs its own appeal process, not the MAC ladder. For a contracted provider, disputes follow the plan's provider dispute procedure in the contract. For a non-contracted provider, the plan must offer a reconsideration within 60 days of the denial, with a waiver of liability that protects the patient. MA plans also carry a rule that matters for pre-authorized services: under 42 CFR 422.138(c), a plan may not later deny coverage for lack of medical necessity on a service it pre-authorized. The approved-then-denied pattern.

The ABN question

Whether a denied service can be billed to the patient depends on whether a valid Advance Beneficiary Notice was signed before the service, and on the group code the remittance carries. Without an ABN on a usually-covered service, the amount is the practice's to absorb. Who can be billed, by group code.