Inpatient Hospital Billing
Facility billing for hospitalized patients, classified using the MS-DRG system under the Acute Inpatient Prospective Payment System.
1 min read · Last reviewed May 23, 2026
At a glance
- Category
- Billing
- Primary sources
- 2
- Workspace handoff
- ask d3 →
Where this comes up
This shows up in revenue-cycle work — claim scrubbing, charge entry, posting, A/R follow-up, and month-end close. Billers and practice managers hit this term when reconciling a payment, working a denial queue, or auditing why a claim aged past 60 days.
Full definition
What it is in practice
CMS pays inpatient hospital stays per MS-DRG with adjustments for wage index, outliers, and capital. Length of stay is one of several inputs.
How it shows up in your practice
Physician practices submit professional claims (CPT/HCPCS) for inpatient services using POS 21. The hospital files the facility claim separately.
Sources
- CMS — Acute Inpatient PPShttps://www.cms.gov/medicare/payment/prospective-payment-systems/acute-inpatient-pps
- CMS — MS-DRG Classifications and Softwarehttps://www.cms.gov/medicare/payment/prospective-payment-systems/acute-inpatient-pps/ms-drg-classifications-and-software
Look up MS-DRG details in Ask D3
Open ask d3 →Related terms
- BillingMS-DRGMedicare Severity Diagnosis Related Groups — the classification system used to pay inpatient hospital admissions under Medicare's prospective payment system.
- BillingTwo-Midnight RuleMedicare policy that generally treats a stay spanning two midnights as appropriate for inpatient admission.
- BillingProfessional ComponentThe portion of a procedure code (designated by modifier 26) representing the physician's interpretation or supervision, separate from the technical component.
D3rx is a healthcare-billing and compliance research aid maintained by D3rx Inc. Articles are drafted by an LLM (Anthropic Claude) against primary HHS, OCR, CMS, eCFR, NIST, and state-regulator publications, and reviewed for restraint and source fidelity by the D3rx team.
Reviewer status: a named credentialed reviewer (CHC, CHPC, or healthcare attorney) is being engaged. Until that engagement is finalized, this page does not claim credentialed review.
Related across the archive
- GlossaryMS-DRGMedicare Severity Diagnosis Related Groups — the classification system used to pay inpatient hospital admissions under Medicare's prospective payment system.
- GlossaryProfessional ComponentThe portion of a procedure code (designated by modifier 26) representing the physician's interpretation or supervision, separate from the technical component.
- GlossaryTwo-Midnight RuleMedicare policy that generally treats a stay spanning two midnights as appropriate for inpatient admission.
- GlossaryICD-10-PCSThe Procedural Coding System used in the United States to report inpatient hospital procedures.
- GlossaryMedicare Part AThe hospital insurance part of Medicare, covering inpatient hospital, skilled nursing facility, hospice, and limited home health.
- BillingAWV + Problem Visit Same Day: How to Bill CorrectlyYes, you can bill AWV and a problem visit the same day. Here's how to do it correctly with modifier -25.
- GlossaryPlace of Service 21 (Inpatient Hospital)Place of service code for services furnished to a patient who has been admitted as an inpatient at a hospital.
- BillingPlace of Service Codes: Which One to Use and Why It Changes Your ReimbursementPOS 11 vs 21 vs 02 vs 10. How the two-digit code on your claim determines whether you get office or facility rates.
This glossary entry is a research aid for billing and compliance staff. It does not provide legal, medical, or financial advice and does not replace counsel. References cited link to primary sources at HHS, OCR, CMS, eCFR, NIST, and the relevant payer or industry body.