What inpatient prospective payment is and why it matters to you

Inpatient Prospective Payment System (IPPS) is the method Medicare uses to pay hospitals a fixed amount for each patient stay, based on the diagnosis and procedures involved rather than the actual costs the hospital incurs. The hospital receives one lump sum per admission, regardless of whether the patient stays three days or two weeks. This system affects what you pay out of pocket and which hospitals accept your Medicare coverage.

The payment amount is set before you arrive — the hospital knows what Medicare will reimburse based on your diagnosis code alone. If the hospital spends less than that amount, it keeps the difference. If it spends more, it absorbs the loss. This creates incentives for hospitals to manage costs and discharge patients efficiently, which can affect your length of stay and the services included in your bill.

Understanding IPPS matters because it shapes your hospital experience, your out-of-pocket costs, and sometimes the timing of your discharge. It also explains why your bill may look different from a neighbor's even if you were treated for the same condition at the same hospital.

Key Takeaways

  • Medicare pays hospitals a flat rate per admission based on your diagnosis, not on how long you stay or what the hospital actually spends.
  • Your out-of-pocket costs under Medicare are based on your deductible and coinsurance, not on the IPPS payment amount.
  • Hospitals have financial incentive to discharge you as soon as medically appropriate, which can affect how long you stay.
  • The IPPS payment rate changes each year and varies by geographic region and hospital type.
  • Private insurance companies use similar systems but with different payment amounts and rules than Medicare.

How the payment amount is calculated

Medicare assigns every hospital admission a Diagnosis-Related Group (DRG) code based on your primary diagnosis, secondary conditions, and any procedures performed. The DRG determines the base payment amount. For example, a simple appendectomy has a different DRG than an appendectomy complicated by infection, and each DRG has its own payment rate.

The base DRG payment is then adjusted for several factors. Geographic location matters — hospitals in high-cost areas receive higher payments than those in rural regions. Hospital type also affects payment: teaching hospitals and those serving low-income patients receive adjustment factors. The final payment amount is what Medicare sends to the hospital, and it covers all routine care, medications, and supplies during your stay.

These rates are published annually by the Centers for Medicare & Medicaid Services (CMS). Hospitals cannot negotiate the IPPS rate for individual patients; the rate is fixed by law. However, hospitals can appeal if they believe a DRG assignment is incorrect, which sometimes happens when medical records do not clearly document secondary diagnoses.

What you pay out of pocket under IPPS

Your out-of-pocket costs are separate from what Medicare pays the hospital. You are responsible for your Part A deductible (the amount you must pay before Medicare coverage begins) and coinsurance (a percentage of costs you share with Medicare). These amounts do not change based on the IPPS payment — they are set by Medicare policy and apply to all hospital stays.

For a typical inpatient stay in 2024, you pay the Part A deductible for the first day, then nothing for days 2 through 60. Days 61 through 90 require coinsurance. Beyond 90 days, costs rise significantly. These thresholds and amounts reset each year and are the same whether your hospital receives a high IPPS payment or a low one.

If you have supplemental insurance (Medigap) or Medicare Advantage, your out-of-pocket costs may be lower because those plans cover some or all of your deductible and coinsurance. The IPPS payment does not affect this either — your supplemental plan's coverage rules determine what you owe.

Why hospitals have incentive to discharge you sooner

Because the hospital receives a fixed payment regardless of length of stay, it has financial incentive to discharge you as soon as you are medically stable. A patient who stays five days costs the hospital more than a patient who stays three days, even though Medicare pays the same amount for both. This is different from the old system, where hospitals were paid for each day of care and had incentive to keep patients longer.

This does not mean hospitals rush you out unsafely. Federal law requires that discharge decisions be based on medical necessity, and hospitals face penalties if they discharge patients prematurely. Your doctor determines when you are ready to leave. However, the financial structure does mean hospitals are motivated to move you toward discharge once you no longer need acute inpatient care — for example, by arranging home health services or rehabilitation facility placement rather than keeping you in the hospital bed.

If you believe you are being discharged too early, you have the right to request a Detailed Explanation of Medicare Benefits (DEMB) and to appeal the discharge decision. Medicare has a formal process for this, and you can request a review by an independent party.

How IPPS differs from what private insurance pays

Private insurance companies use similar systems — they also pay hospitals a negotiated rate per admission rather than paying for each day or service. However, the rates are different from Medicare's IPPS rates and are negotiated between the insurance company and each hospital. A hospital may receive a higher or lower payment from Aetna than from Medicare for the same diagnosis.

Private insurance also uses different coding systems in some cases and may have different rules about what is covered. Some private plans require pre-authorization before admission, meaning the insurance company must approve the hospital stay in advance. Medicare does not require pre-authorization for emergency admissions, though it does for planned procedures at some hospitals.

If you have both Medicare and private insurance, Medicare is the primary payer and the private plan is secondary. The hospital bills Medicare first, and the private plan may cover some or all of your remaining out-of-pocket costs depending on your plan.

Changes to IPPS rates and how to find your hospital's payment

CMS updates IPPS payment rates every October for the fiscal year beginning October 1. The rates are published in the Federal Register and on the CMS website. Rates typically increase by a small percentage each year to account for inflation, though the exact increase varies by hospital type and region.

You can look up what Medicare pays for a specific DRG at a specific hospital using the CMS Inpatient Prospective Payment System Pricer tool on the CMS website. You enter your diagnosis code and hospital, and the tool shows you the payment amount. This is public information and can help you understand what Medicare is paying for your care, though it does not predict your personal out-of-pocket cost.

If you are planning a hospital procedure and want to understand costs in advance, call the hospital's billing department and ask for an estimate based on your diagnosis. They can tell you the expected DRG, the IPPS payment amount, and your likely out-of-pocket cost based on your insurance coverage.

What happens if the hospital's costs exceed the IPPS payment

If a hospital spends more money treating you than the IPPS payment covers, the hospital absorbs the loss. This is why hospitals focus on efficiency — they cannot bill you or Medicare for the overage. Conversely, if the hospital spends less than the payment, it keeps the surplus. This financial risk is part of why hospitals invest in technology, staff training, and process improvement.

In rare cases, a hospital may face financial hardship if too many patients require more intensive care than the DRG payment assumes. Hospitals can request outlier payments from Medicare if a patient's care is unusually expensive — for example, if you develop a serious complication that requires extended ICU care. These outlier payments are additional to the base IPPS payment and are designed to protect hospitals from catastrophic losses on individual cases.

This system is one reason why hospital consolidation has increased — larger hospital systems can spread financial risk across many patients and locations, while small hospitals may struggle to absorb losses on complex cases.

Frequently Asked Questions

Does the IPPS payment amount affect what I pay out of pocket?

No. Your out-of-pocket costs are determined by your Medicare deductible and coinsurance, which are set by Medicare policy and do not change based on the IPPS payment. Whether the hospital receives a high payment or low payment for your diagnosis, you pay the same amount.

Can a hospital refuse to treat me because the IPPS payment is too low?

No. Hospitals that accept Medicare must treat all Medicare patients regardless of the DRG payment amount. Refusing care based on payment would violate federal law. However, some hospitals may limit certain services or specialties based on financial sustainability.

What is a DRG code and who assigns it?

A DRG code is a classification that groups patients by diagnosis and procedures. Hospital coders assign the DRG based on your medical record after discharge. The code determines the IPPS payment amount. If you believe the code is wrong, you can ask the hospital to review it, and Medicare can also investigate if you file an appeal.

Does the IPPS payment include all my medications and supplies during my stay?

Yes. The IPPS payment covers routine medications, supplies, and services provided during your inpatient stay. Medications you take home after discharge may be covered under Medicare Part D (prescription drug coverage) instead, which has separate costs.

How do I know if my hospital stay qualifies as inpatient under IPPS?

Your doctor and the hospital determine your admission status. Inpatient means you are admitted to the hospital and expected to stay at least one night. Observation status is different — it is a shorter stay that may be billed differently and may have different out-of-pocket costs. If you are unsure of your status, ask the hospital billing department or your nurse.