How to Dispute a Medicare Bill: Appeals, Deadlines & the 4-Level Process

MSN vs. EOB: Know Your Documents

Before you can dispute anything, you need to know which document you're looking at.

Your Medicare Summary Notice (MSN) is the official record Medicare sends you quarterly, listing every service billed to Original Medicare (Parts A and B) on your behalf. It shows the amount billed, the Medicare-approved amount, what Medicare paid, and the maximum you can legally be charged. The MSN is not a bill—it is your audit tool.

An Explanation of Benefits (EOB) comes from a private insurer—your Medicare Advantage plan, Medigap policy, or other secondary insurer. If you have Medicare Advantage, your EOB is the primary billing document (you won't receive an MSN for those claims). If you have Medigap, your EOB shows what the supplemental plan paid after Medicare.

Key actions when you receive either document:

• Compare the provider name and service date to your own records
• Verify the billed amount matches the itemized bill you received from the provider
• Check that Medicare's approved amount matches the fee schedule (available at cms.gov)
• Confirm the "amount you may be billed" on your MSN matches what the provider actually charged
• Flag any services you don't recognize or dates when you were not treated

When to Dispute a Medicare Bill

Not every billing discrepancy requires a formal appeal. Some errors resolve with a single phone call to 1-800-MEDICARE or directly to the provider. A formal dispute is appropriate when:

• Your bill exceeds the "amount you may be billed" shown on your MSN
• Medicare denied a claim you believe is covered
• You were charged for a service you never received
• You were billed as "outpatient observation" but believe you should have been admitted as an inpatient
• A provider billed more than the Medicare limiting charge (115% of the fee schedule for non-participating providers)
• You were discharged from the hospital before you felt medically ready

The 4 Levels of Medicare Appeals

Original Medicare has a structured, four-level appeal process. Each level is independent, and each has its own deadline and decision-maker.

Level 1: Redetermination

File with your Medicare Administrative Contractor (MAC) within 120 days of your MSN date. The MAC is the regional contractor that processed the original claim. Submit a written request explaining the error, attach your MSN, and include any supporting documentation (itemized bills, physician letters, medical records).

The MAC must respond within 60 days for Part B claims and 60 days for Part A claims. Most straightforward billing errors are resolved here.

Level 2: Reconsideration

If your Level 1 appeal is denied, file for reconsideration with a Qualified Independent Contractor (QIC) within 180 days of the MAC's decision. The QIC is entirely independent of the MAC—this is a fresh review. The QIC must respond within 60 days.

For Medicare Advantage appeals, the equivalent of Level 2 is an external review organization rather than a QIC.

Level 3: ALJ Hearing

If denied at Level 2, you may request a hearing before an Administrative Law Judge (ALJ) within 60 days of the QIC decision. A threshold applies: the amount in dispute must be at least $180 in 2026. ALJ hearings can be conducted in person, by phone, or by video. You can present witnesses, submit evidence, and be represented by an attorney or advocate.

Level 4: Medicare Appeals Council

If the ALJ rules against you, you can appeal to the Medicare Appeals Council within 60 days. The Council reviews the record without a new hearing. Federal court review is available after the Council exhausts its review, for disputes meeting a higher dollar threshold ($1,870 in 2026).

Fast-Track Appeals for Inpatient Stays

Standard Medicare appeals take weeks or months. If you are currently hospitalized and being discharged before you believe you are medically ready, standard timelines are useless. That is what fast-track (expedited) appeals are designed for.

Under an expedited appeal, you contact your state's Quality Improvement Organization (QIO) before or on the day of discharge. The QIO must make a decision by midnight of the day after it receives your request. You cannot be discharged while the appeal is pending.

Fast-track appeals apply when:

• You are being discharged from an inpatient hospital and believe you need to stay longer
• You are being discharged from a skilled nursing facility, home health, or comprehensive outpatient rehab, and you believe the services should continue

If the QIO sides with the hospital, you may still appeal to a QIC for a second-level expedited review. You have 72 hours from the QIO's fast-track decision to request QIC review.

The QIO's Role

Quality Improvement Organizations are CMS-contracted entities in each state that serve two key Medicare functions: (1) reviewing and improving quality of care, and (2) handling beneficiary complaints and expedited appeals.

For billing disputes, the QIO's most important role is the fast-track discharge appeal described above. But QIOs also handle written complaints about quality of care, premature discharge, and hospital observation status classification.

To find your state's QIO, visit qioprogram.org or call 1-800-MEDICARE. Have your Medicare number, hospital name, and discharge date ready.

Key Deadlines at a Glance

• 120 days from MSN: File a Level 1 redetermination
• Before or day of discharge: Contact QIO for a fast-track inpatient appeal
• 180 days from Level 1 denial: File Level 2 reconsideration
• 60 days from Level 2 denial: Request ALJ hearing
• 60 days from ALJ decision: Appeal to Medicare Appeals Council

How to File a Level 1 Appeal Step by Step

1. Get your MSN. If you haven't received one, log in to Medicare.gov or call 1-800-MEDICARE to request it.
2. Get your itemized bill. Ask the provider for a line-by-line itemized bill with CPT codes. Compare every charge to your MSN.
3. Write your dispute letter. State the claim number, service date, provider name, and the specific error. Be concise: one page is enough for most billing disputes.
4. Attach supporting documents. Include your MSN, the provider's bill, any medical records showing the service was or was not rendered, and a physician letter if available.
5. Send to your MAC. The address is printed on your MSN. Send by certified mail and keep a copy of everything.
6. Track the response. The MAC has 60 days. If you don't hear back, call and reference your certified mail tracking number.

Using 1-800-MEDICARE

The 1-800-MEDICARE line (1-800-633-4227) is available 24 hours a day, 7 days a week. Use it to:

• Get the status of a specific Medicare claim
• Request a copy of your MSN
• Report a billing error before filing a formal appeal
• Find the address of your Medicare Administrative Contractor
• File an informal complaint against a provider

TTY users can call 1-877-486-2048. Spanish-language support is available at the same number.

• Medicare.gov — How to File an Appeal
• CMS — Medicare Appeals and Grievances
• QIO Program — Find Your State QIO
• HHS Office of Medicare Hearings and Appeals (OMHA)