Overview
The UB-04 is the standard institutional billing form used by hospitals, skilled nursing facilities, home health agencies, hospices, rural health clinics, federally qualified health centers, and other institutional providers. Also known as the CMS-1450, the UB-04 was developed and is maintained by the National Uniform Billing Committee (NUBC) in consultation with CMS. Its electronic equivalent — the ASC X12 Health Care Claim Institutional, or 837I — is HIPAA-mandated and is the form in which the overwhelming majority of institutional claims actually transmit.
UB-04 contains 81 form locators (FLs) covering provider information (FL 1–6), patient demographics (FL 8–15), dates and type of service (FL 6, 12–13, 42, 45), revenue code lines with units and charges (FL 42–48), payer information (FL 50–66), diagnoses (FL 66–75, up to 25 ICD-10-CM codes with separate admit/principal/secondary designations), procedures (FL 74 for inpatient, mapping to ICD-10-PCS), and provider identifiers (FL 76–81). The revenue code system is a key distinguishing feature — each service line uses a UB revenue code (four-digit code) that identifies the category of service, paired with HCPCS/CPT codes where applicable.
UB-04 revenue coding is operationally important: each line's revenue code places the charge in a cost center such as laboratory, operating room, anesthesia, emergency department or drugs that need detailed HCPCS coding. The NUBC maintains the code list and licenses its descriptions through the Official UB-04 Data Specifications Manual. Correct revenue code assignment drives both facility charge capture and payer adjudication. A laboratory test posted under a revenue code from the wrong cost center is a common cause of line-level denials.
Differences from CMS-1500 are significant. UB-04 uses revenue codes, diagnosis codes with POA indicators, admit diagnosis distinct from principal, ICD-10-PCS procedure coding (for inpatient), and bill-type coding (FL 4) that identifies facility type and billing frequency (inpatient discharge, inpatient interim, outpatient, etc.). UB-04 also includes occurrence codes, condition codes, value codes, and span codes that provide adjudication-critical context — things like "catastrophic injury date," "no-fault insurance involvement," "birth weight of newborn."
For RCM, institutional claim quality depends on chargemaster accuracy (CDM drives revenue codes and HCPCS/CPT assignment), charge-capture discipline (ensuring all chargeable services post to the claim), coding accuracy (ICD-10-CM diagnoses with POA, ICD-10-PCS procedures), and UB-04-specific fields (occurrence, condition, value codes as applicable). Pre-bill edit engines — often built from NCCI-IOCE (Integrated Outpatient Code Editor) or NCD/LCD policy databases — catch errors before submission.
Like CMS-1500, paper UB-04 submission is rare. HIPAA mandates electronic submission for most providers, and 837I is the operational reality. Paper UB-04 persists for appeals, special circumstances, and small-volume providers under specific exemptions.
Industry benchmark
NUBC UB-04 Manual (annually updated). HIPAA ASC X12N TR3 837 Institutional Implementation Guide. CMS Pub 100-04 Claims Processing Manual Chapters specific to institutional billing.
Worked example
A hospital inpatient discharge. UB-04 fields: FL 4 type of bill for an inpatient admit-through-discharge claim; FL 6 from-through dates; FL 42 revenue codes for each cost center (room and board, laboratory, operating room, emergency department); FL 67 principal diagnosis I21.4 (acute STEMI); FL 74 principal procedure 02703DZ (PCI with drug-eluting stent); FL 76–77 attending and operating provider NPIs. Total charges $184,000; expected IPPS payment per MS-DRG 246 approximately $32,500. Electronic submission via 837I in < 1 minute.
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Frequently asked questions — UB-04 (Institutional Claim Form)
Who uses UB-04?
Institutional providers: hospitals, SNFs, home health agencies, hospices, end-stage renal disease facilities, rural health clinics, federally qualified health centers, critical access hospitals, and similar facility-based providers. Individual physicians and non-physician practitioners use CMS-1500 instead.
What's a UB revenue code?
A four-digit code that identifies the category of service on an institutional claim. Revenue codes pair with HCPCS/CPT codes where applicable to identify both the revenue category and the specific service. Revenue code systems are maintained by NUBC.
What is the bill type field?
FL 4 on the UB-04 is a three- or four-character Type of Bill code that identifies the facility type (first digit), bill classification — inpatient, outpatient, etc. (second digit), and frequency — admit-through-discharge, interim, etc. (third digit). The NUBC publishes the code values and their meanings in the UB-04 data specifications.
How does UB-04 handle multiple diagnoses?
Up to 25 ICD-10-CM diagnoses (principal plus secondary), with POA (present-on-admission) indicators for each secondary diagnosis. POA is critical for MS-DRG assignment because certain hospital-acquired conditions (POA = N) do not count as MCCs/CCs for payment. Separate admit diagnosis is captured in FL 69.
CMS guidance
The Medicare Learning Network publication that CMS issues on this topic, cited by ICN and publication date:
- Medicare Billing: CMS-1450 & 837I(MLN006926, )Completing the CMS-1450 (UB-04) and its electronic 837I equivalent for institutional claims.
Disclaimer
This glossary entry is operational reference for revenue-cycle and medical-billing professionals. It is not legal, clinical, or contractual advice. Industry benchmarks cite named public sources where available; always verify against the current guidance from the authority body before relying on a number in a contract, policy, or compliance filing.