If your insurer denied an inpatient hospital claim, you have 180 days from the date of the denial notice to file an internal appeal, and if that appeal fails, four months to request an independent external review whose decision binds the insurer. That is the inpatient claim denial appeal process in its simplest form, and the deadlines are strict. Everything else — what to put in the appeal, whether to try a peer-to-peer first, whether Medicare rules change the path — turns on why the claim was denied and who issued the denial.
Why Inpatient Claims Get Denied
Before you write anything, find out exactly why the insurer said no. The reason shapes the appeal.
The most consequential denial is a level-of-care denial. The insurer reviews your medical record after discharge and decides your condition did not justify inpatient admission, arguing the care should have been provided on an outpatient or observation basis. This is where most of the money is at stake, and it is also the hardest denial to overturn without strong physician documentation.
Other denials come from process failures rather than medical judgment:
- Missing prior authorization. Many commercial insurers require advance approval for inpatient stays. Emergency admissions typically get a grace period for retroactive authorization, but missing the deadline can trigger an automatic denial even when the stay was medically necessary.
- Coding errors. An incorrect DRG assignment or mismatched diagnosis codes can cause a denial or reduced payment. Sometimes the insurer downgrades the DRG, arguing the documentation does not support the higher-severity code the hospital assigned.
- Insufficient documentation. Even when the physician’s clinical judgment clearly supports admission, the claim can be denied if the medical record does not adequately document the reasoning. Insurers review what is written, not what was thought.
There is also the continued-stay denial, issued while you are still in the hospital. Many insurers conduct concurrent utilization review and may decide partway through your stay that additional days are not medically necessary. You can appeal these denials too, and knowing the review is happening gives you time to make sure your physician documents why each additional day is needed.
Try a Peer-to-Peer Review First
Before or alongside a formal appeal, insurers sometimes offer a peer-to-peer review, where your treating physician speaks directly with a physician representing the insurer. If your doctor is willing to make the call, this can resolve a denial faster than a written appeal. Insurers do not always make the calls easy to schedule, so ask your physician’s office whether a peer-to-peer has been offered and whether it has been completed. If it was never attempted or never connected, that is worth knowing before you file.
Filing the Internal Appeal
The internal appeal is a written request to your insurer to reconsider the denial. You have 180 days from the date you receive the denial notice to submit it.1HealthCare.gov. Internal Appeals Do not assume the hospital will handle this. Providers sometimes appeal on their own behalf, but you should file independently to protect your own rights.
A strong appeal package has three parts:
- A written statement from you explaining in plain language why the denial is wrong, pointing to specific medical facts.
- Complete medical records from the hospitalization, plus any earlier records that establish the severity of your condition.
- A letter from your treating physician. This is the most important piece. The physician should directly address the insurer’s stated reason for denial and explain why inpatient care was medically necessary. Vague letters do not help. The physician needs to connect your specific clinical situation to the criteria the insurer is applying.
If your coverage comes through an employer, the plan is almost certainly governed by ERISA, and the stakes of the internal appeal rise sharply. Under ERISA, you generally cannot sue the plan until you have exhausted internal appeals, and courts typically limit their review to the evidence that was in the record at the time the plan made its final decision. Anything you leave out now may be excluded later. Treat the internal appeal as your one chance to build the strongest possible case.
External Review
If the insurer upholds the denial after the internal appeal, you have the right to an external review by an independent third party with no connection to the insurer. Federal law requires health plans to either use their state’s external review process or follow a federal process that meets minimum standards set by HHS.2Office of the Law Revision Counsel. 42 USC 300gg-19 – Appeals Process
You must file a written request for external review within four months of receiving the final internal denial. Standard external reviews are decided no later than 45 days after the request is received. For urgent medical situations, an expedited external review is decided within 72 hours or less depending on the circumstances.3HealthCare.gov. External Review
The reviewer’s decision is binding. If the reviewer rules in your favor, the insurer must pay the claim. This is not a recommendation the insurer can disregard; it is required by law to comply.3HealthCare.gov. External Review
Medicare: Appealing a Status Reclassification
Medicare beneficiaries face a specific problem when a hospital initially admits them as inpatients and then reclassifies the stay to observation status. Following the ruling in Alexander v. Azar, CMS established both expedited and standard appeal processes for eligible beneficiaries who disagree with this reclassification. The expedited process is available while you are still in the hospital; the standard process applies if you did not file an expedited appeal during the stay.4Centers for Medicare & Medicaid Services. Medicare Appeal Rights for Certain Changes in Patient Status
This appeal right is narrow. It does not apply to patients placed in observation status from the start. It applies only when you were first admitted as an inpatient and the hospital later changed the classification. If this happens, ask the hospital for written notice of the reclassification and act quickly, because the expedited timeline is short.
If You Are Still in the Hospital: Challenging a Discharge
Appeals do not always wait for discharge. If you are a Medicare beneficiary and believe you are being sent home too soon, you can request an immediate review from the Quality Improvement Organization (QIO) in your area. The request must be made no later than the day of your planned discharge and can be submitted by phone or in writing. While the QIO reviews your case, the hospital generally cannot charge you for inpatient services through at least noon of the day after the QIO issues its decision.5eCFR. 42 CFR 422.622 – Requesting Immediate QIO Review
The QIO phone number appears on the Important Message from Medicare, a notice the hospital is required to give you within two days of inpatient admission. If you cannot find your copy, the hospital must provide the number. Do not wait until the last moment. If you suspect a premature discharge is coming, alert your physician so the medical record reflects the ongoing need for inpatient care.
A Note on Inpatient Versus Observation
Many denials turn on this distinction, so it is worth understanding what the insurer is actually arguing. Inpatient status requires a formal physician order admitting you to the hospital, backed by a determination of medical necessity.6Centers for Medicare & Medicaid Services. Hospital Inpatient Admission Order and Certification Under CMS’s Two-Midnight Rule, inpatient admission is generally appropriate when the admitting physician expects care to cross at least two midnights, based on documented medical factors. What matters is the physician’s expectation at the time of admission, not the actual length of stay.7GovInfo. 42 CFR 412.3 – Admissions Observation status is classified as outpatient care, even when it involves overnight stays, and it carries different cost-sharing. If the denial recharacterizes your stay as something that should have been observation, your appeal has to attack that recharacterization directly, with the physician’s documented reasoning at the time of admission as the centerpiece.
If the Appeal Fails: Financial Assistance
If every appeal fails and you are left with a large bill, nonprofit hospitals may still reduce what you owe. Under Section 501(r) of the Internal Revenue Code, tax-exempt hospitals must maintain a written financial assistance policy covering all emergency and medically necessary care. The policy must include eligibility criteria, the basis for calculating reduced charges, and instructions for applying. Hospitals cannot charge patients who qualify more than the amounts generally billed to insured patients.8eCFR. 26 CFR 1.501(r)-4 – Financial Assistance Policy and Emergency Medical Care Policy
Ask the billing department for an application. Many patients who would qualify never apply because they do not realize the program exists. The notices are easy to miss, and applying costs nothing.