UB-04 Form in Medical Billing: Complete 2025 Guide to CMS-1450, 837I Claims, and Institutional Billing Compliance

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In facility-based healthcare billing, the UB-04 form is a cornerstone document, pivotal to the revenue cycle for institutional providers like hospitals, nursing homes, and rehabilitation centers. Also known as the CMS-1450 form, the UB-04 is the universal claim form used by institutional providers to bill services rendered to patients in inpatient and outpatient settings.

Unlike the CMS-1500 form, which is primarily used by individual healthcare providers and physicians, the UB-04 form is designed for hospitals, skilled nursing facilities, home health agencies, rehab centers, and other institutions that bill Medicare, Medicaid, TRICARE, and commercial payers.

Developed by the National Uniform Billing Committee (NUBC), the UB-04 is used for both paper claims and electronic submissions (via the 837I format) and ensures that medical claims are submitted in a standardized, payer-accepted layout.

Whether you are billing for a routine outpatient procedure or a complex inpatient hospital stay, mastering the UB-04 form is essential for ensuring timely reimbursement, claim acceptance, and revenue cycle efficiency.

In this MedStates UB-04 guide, we will walk you through everything you need to know—from field-by-field instructions and common denial codes to payer-specific requirements and billing best practices—so your facility can improve its clean claim rate and avoid costly errors.

Did you know? A simple mistake on the UB-04 could delay payments or even lead to costly fines for a healthcare provider. Keep reading to discover how these small errors could have major consequences!

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What Is UB-04 Form in Medical Billing?
UB-04 vs CMS-1500 – A Deep Comparison of Billing Forms
Providers and Facilities That Use the UB-04
Detailed Field-by-Field Explanation of UB-04 (Form Locator Boxes 1–81)
Key Elements Unique to the UB-04 Form
Most Common UB-04 Errors (and How to Prevent Them)
UB-04 vs. CMS-1500 – Key Differences in Billing Forms
UB-04 Billing Guidelines by Payer (Medicare, Medicaid, and Commercial)
UB-04 in Electronic Claim Submission (837I File Format)
Frequently Asked Questions on UB-04

What Is UB-04 Form in Medical Billing?

The UB-04 form, officially designated as the CMS-1450, is the standardized medical billing form used by institutional healthcare providers to submit claims for reimbursement. Introduced by the Centers for Medicare & Medicaid Services (CMS) in collaboration with the National Uniform Billing Committee (NUBC), the UB-04 replaced its predecessor (UB-92) to modernize and streamline billing across the U.S. healthcare system.

This form is specifically tailored for facilities that deliver inpatient, outpatient, and long-term care services, including:

Acute care hospitals
Skilled nursing facilities (SNFs)
Inpatient rehabilitation centers
Behavioral health institutions
Home health agencies
Hospice and long-term care facilities

Whereas individual healthcare practitioners bill using the CMS-1500 form, UB-04 is the institutional claim form designed for organizations that manage patient stays, use multiple departments, and generate complex billing scenarios.

Paper and Electronic Formats

While the UB-04 form is available in paper format, the vast majority of claims today are submitted electronically using the 837I transaction set, which mirrors the UB-04 field structure but complies with HIPAA electronic data interchange (EDI) standards. Regardless of submission method, every field on the form must be filled out with precise codes and data—including diagnosis codes (ICD-10-CM), revenue codes, HCPCS or CPT codes, NPI numbers, and payer details. The structure of the UB-04 supports efficient automated claims processing, which is critical to revenue cycle management (RCM).

Core Purpose of the UB-04 Form

Submit claims for hospital and facility-based services to Medicare, Medicaid, and private payers
Capture institutional data elements, such as patient status, admission type, and discharge disposition
Align facility claims with coding standards, payer-specific rules, and federal billing regulations
Enable the uniformity needed for national reimbursement systems like DRG and APC
Document a wide range of services—from room and board charges to diagnostic imaging and surgical care

Why the UB-04 Matters in Medical Billing

A single claim error on the UB-04 can delay payment by weeks—or lead to a denial altogether. That’s why institutional providers rely on accurate completion and deep knowledge of how this form interacts with revenue codes, diagnosis coding, and payer contracts. When completed correctly, it supports:

Faster reimbursements
Fewer denials and rejections
Improved claim audit results
Compliance with payer policy and CMS rules

For Insurance Credentialing, Medical Billing Services and other services

UB-04 vs CMS-1500 – A Deep Comparison of Billing Forms

Understanding the difference between the UB-04 form and the CMS-1500 form is crucial for accurate claim submission in the U.S. healthcare system. Though both are used to bill health insurance payers, they serve distinct functions, are used by different types of providers, and are submitted in different formats.

UB-04 vs CMS-1500: Feature Comparison Table

Feature	UB-04 (CMS-1450)	CMS-1500
Used By	Hospitals, SNFs, Facilities	Physicians, Non-facility providers
Claim Type	Institutional	Professional
Electronic Equivalent	837I	837P
Billing For	Room & board, facility fees, labs	Physician time, services, consultations
Coding Systems Used	ICD-10-CM, HCPCS, Revenue Codes	ICD-10-CM, HCPCS, CPT
Submission Complexity	Higher – more fields & codes	Simpler – fewer claim elements
Reimbursement Models	DRG, APC, per diem, per visit	Fee-for-service (FFS)

When to Use Each Form

Use CMS-1500 when a licensed medical professional is billing directly for their time, expertise, or services.
Use UB-04 when a facility is billing for inpatient stays, outpatient visits, or services involving facility overhead, such as operating rooms, ICU, and nursing units.

Example Scenarios:

A physician seeing a patient in a clinic: CMS-1500
A patient receiving outpatient surgery at a hospital: UB-04
Physical therapist billing privately: CMS-1500
Home health services billed under Medicare: UB-04

Providers and Facilities That Use the UB-04

The UB-04 form in medical billing is not a one-size-fits-all tool—it is purpose-built for institutional healthcare providers that render services in facilities rather than in office settings. Unlike the CMS-1500 form used by physicians and private practitioners, the UB-04 supports the complex billing needs of healthcare institutions that deliver coordinated, multi-department services over multiple days or episodes of care.

Common Providers That Use the UB-04 Form

1. Acute Care Hospitals

Used for both inpatient and outpatient services
Bill for room and board, surgery, ICU, labs, diagnostics, and emergency department services
DRG-based reimbursement under Medicare

2. Skilled Nursing Facilities (SNFs)

Submit claims for long-term care or post-acute rehab stays
Include therapies (PT/OT/ST), nursing care, medications, and room charges
Must comply with Medicare Part A SNF Consolidated Billing (CB) requirements

3. Inpatient Rehabilitation Facilities (IRFs)

Use UB-04 to bill for intensive rehabilitation programs such as stroke, spinal cord injury, or post-surgical therapy
Captures functional status codes, physician visits, nursing services, therapy hours

4. Psychiatric and Behavioral Health Hospitals

Bill for psychiatric admissions, crisis stabilization, and behavioral therapy sessions
Requires precise documentation for diagnosis, length of stay, and discharge planning

5. Long-Term Care Hospitals (LTCHs)

Serve patients requiring extended hospital-level care (typically >25 days)
Complex claims include ventilator use, infection control, wound care, and respiratory therapy

6. Hospice Care Providers

UB-04 is used to bill for Medicare-certified hospice services
Includes home visits, inpatient respite care, and palliative medications

7. Home Health Agencies (HHAs)

Submit claims via UB-04 under Medicare Part A and Medicaid
Use HIPPS codes, visit type, frequency, and OASIS assessments

8. Federally Qualified Health Centers (FQHCs) and Rural Health Clinics (RHCs)

When billing for institutional-type services (e.g., in-clinic infusions or behavioral therapy), UB-04 is used
Special payment structures apply (e.g., encounter-based)

9. Ambulatory Surgery Centers (ASCs) (when part of a hospital system)

If owned and operated by hospitals, ASCs may use UB-04 for outpatient surgery claims
Otherwise, CMS-1500 is used by independent ASCs

Summary of Facility Types Using UB-04

Facility Type	Billing via UB-04?	Notes
Acute Care Hospital	✅ Yes	Inpatient & outpatient billing
Skilled Nursing Facility (SNF)	✅ Yes	Part A and Part B Medicare services
Inpatient Rehab Facility (IRF)	✅ Yes	Rehabilitation-focused services
Home Health Agency (HHA)	✅ Yes	OASIS-based claims, home visits
Hospice Care Provider	✅ Yes	Palliative services under Medicare hospice benefit
Long-Term Care Hospital (LTCH)	✅ Yes	Ventilation, extended inpatient services
Behavioral Health Hospital	✅ Yes	Mental health admissions and therapy billing
Ambulatory Surgery Center (Hospital)	✅ Sometimes	Only if part of hospital system
Private Practice / Physician Clinic	❌ No	CMS-1500 is used

Detailed Field-by-Field Explanation of UB-04 (Form Locator Boxes 1–81)

To accurately complete the UB-04 form in medical billing, billers must understand the meaning and usage of each Form Locator (FL)—the numbered fields that capture all required data for institutional claims. There are 81 Form Locators on the UB-04, though not all are used in every claim. Below is a breakdown of the most critical fields, grouped by category, with explanations and tips.

Provider & Facility Information (FL 1–8)

Form Locator	Description	Example / Notes
FL 1	Provider Name, Address	Legal name of hospital or facility
FL 2	Pay-to Name, Address	Where payments should be sent (optional in many cases)
FL 3a / 3b	Patient Control Number / Medical Record #	Unique ID for internal tracking
FL 4	Type of Bill	3-digit code: Facility type + bill classification + frequency
FL 5	Federal Tax Number	EIN used for tax and payer identification
FL 6	Statement Covers Period	Service start and end date (e.g., admission to discharge)
FL 7	Reserved for Assignment by CMS	Leave blank unless instructed by payer
FL 8a–8b	Patient ID and Birth Date	Demographics for patient identification

Patient & Subscriber Information (FL 9–17)

FL	Description	Example / Notes
FL 9	Patient Address	Full street address, city, state, and ZIP code
FL 10	Patient’s Sex	M / F / U (unknown)
FL 11–12	Admission Date and Hour	Especially important for inpatient or ER billing
FL 13	Admission Type	Urgent, elective, trauma, etc.
FL 14	Admission Source	Physician referral, transfer from another facility
FL 15	Point of Origin for Admission	Required for some inpatient and outpatient billing
FL 16	Discharge Hour	24-hour time format
FL 17	Discharge Status	Indicates where the patient went after discharge

Payer Information & Insurance Details (FL 50–65)

FL	Description	Example / Notes
FL 50	Payer Name	Medicare, Medicaid, BCBS, etc.
FL 51	Health Plan ID	Usually optional
FL 52	Release of Information Indicator	Y/N
FL 53	Assignment of Benefits Indicator	Y/N
FL 54	Prior Payments	Amounts paid by other insurers
FL 55	Estimated Responsibility	Patient’s estimated financial portion
FL 56	National Provider Identifier (NPI)	Billing provider’s NPI
FL 58–60	Insured Name, ID, Group Number	Payer-specific details
FL 61–65	Employer, Plan Name, Release Info	As required by insurer

Revenue & Procedure Coding (FL 42–49)

FL	Description	Notes
FL 42	Revenue Code	4-digit codes identifying type of service (e.g., 0300 = Lab)
FL 43	Revenue Description	Short label for service (e.g., Blood Test)
FL 44	HCPCS/Rates	CPT/HCPCS codes for outpatient claims
FL 45	Service Date	Date of individual service rendered
FL 46	Units of Service	Number of units billed
FL 47	Total Charges	Total charges per revenue code line
FL 48	Non-covered Charges	Amount not covered by payer
FL 49	Reserved for Future Use	Typically left blank

Diagnosis & Procedure Codes (FL 67–74)

FL	Description	Notes
FL 67	Principal Diagnosis Code	ICD-10-CM code primarily responsible for services
FL 67A–Q	Other Diagnosis Codes	Additional conditions affecting care
FL 69	Admitting Diagnosis	Condition as diagnosed at time of admission
FL 70A–C	Patient’s Reason for Visit Codes	Often used in outpatient billing
FL 71	Prospective Payment System (PPS) Code	DRG/APC codes for Medicare reimbursement
FL 72	External Cause of Injury Codes	ICD-10-CM external cause codes (e.g., fall, MVA)
FL 74	Principal Procedure Code & Date	For inpatient surgical/medical procedures

Attending and Referring Provider Data (FL 76–79)

FL	Description	Example / Notes
FL 76	Attending Provider NPI	Required for all claims
FL 77	Operating Physician NPI	For surgical or interventional procedures
FL 78	Other Provider	Consulting or referring physician
FL 79	Additional Physician	Optional depending on claim complexity

Special Codes and Miscellaneous (FL 18–41, FL 80–81)

FL	Description	Notes
FL 18–28	Condition Codes	Define special conditions (e.g., hospice, accident involvement)
FL 29–34	Accident/Injury Dates	Auto, work, or liability injury information
FL 35–36	Occurrence Codes and Dates	Key events affecting billing (e.g., onset of symptoms)
FL 39–41	Value Codes and Amounts	Medicare-specific financial details (e.g., deductible amounts)
FL 80	Remarks	Free-text for payer instructions or documentation
FL 81	Taxonomy Codes and Additional Info	Used for legacy codes or billing-specific details

Key Elements Unique to the UB-04 Form

Key Fields That Define the UB-04 Form

While most healthcare billing forms collect patient and provider details, the UB-04 includes specialized fields that classify institutional services with much finer granularity. These fields are crucial to payer reimbursement and often misunderstood by general billers.

1. Type of Bill (FL 4)

A 3-digit code that summarizes:

Facility type (e.g., hospital, SNF)
Bill classification (e.g., inpatient, outpatient)
Frequency (e.g., original, corrected, voided)

Format: XXX → 1st digit = facility, 2nd = care type, 3rd = bill frequency

Example:
111 = Hospital, Inpatient, Original Claim
331 = SNF, Inpatient, Original Claim

📌 Used by payers to route the claim to the correct adjudication process.

2. Revenue Codes (FL 42)

A 4-digit numeric code used to categorize services rendered.
Each revenue code corresponds to a cost center within the facility.

Revenue Code	Description
0100	Room and Board
0250	Pharmacy
0300	Laboratory Services
0420	Physical Therapy
0450	Emergency Room

➡️ Revenue codes are essential for Medicare and Medicaid payment grouping systems like DRG, APC, or per diem.

3. Occurrence Codes and Dates (FL 31–34)

Used to report significant events or dates that impact the billing or eligibility.
Tied to coverage start/stop, accident dates, or qualifying periods.

Examples:

11 = Date of onset of symptoms
50 = Date beneficiary became eligible for Medicaid

4. Condition Codes (FL 18–28)

Two-character alphanumeric codes used to explain unusual billing conditions or circumstances.

Code	Meaning
04	Information only bill (no payment requested)
20	Beneficiary requested billing
44	Inpatient admission changed to outpatient

📌 Helps flag claims for special payer processing rules.

5. Discharge Status Code (FL 17 or FL 6X range)

Indicates the patient’s disposition at the end of service.
Used in DRG payment systems to determine reimbursement accuracy.

Code	Status Description
01	Discharged to home
02	Discharged to another facility
20	Expired

🧠 Critical for Medicare post-acute care payment calculations.

6. Value Codes (FL 39–41)

These codes communicate monetary amounts related to benefits, deductibles, or benefit days used.

Code	Status Description
01	Most recent semi private room rate
12	Working Aged beneficiary/spouse with employer group health plan
80	Covered days

7. Form Locator 81 – Additional Codes

Used for reporting:

Taxonomy codes
Legacy provider IDs
Condition-specific identifiers (e.g., trauma registry numbers)

May also be used for payer-specific overrides or edits.

Most Common UB-04 Errors (and How to Prevent Them)

Even experienced billers can make mistakes when completing the UB-04 (CMS-1450) form. Since institutional billing claims go through stringent edits (especially by Medicare, Medicaid, and commercial payers), even a minor inconsistency can lead to denials or delays. Here are the most frequent UB-04 errors—along with clear tips to avoid them:

1. Incorrect or Missing Type of Bill Code (FL 4)

❌ Error: Using the wrong bill type (e.g., outpatient instead of inpatient)

🔎 Impact: Claim processed incorrectly or rejected entirely

✅ Fix: Always confirm the 3-digit TOB code against payer policy for the service type and visit frequency.

2. Mismatched Revenue Codes and HCPCS (FL 42 & 44)

❌ Error: Using a revenue code that doesn’t align with the HCPCS/CPT

🔎 Impact: Suspended claims, underpayment, or denial

✅ Fix: Refer to payer-specific revenue code-HCPCS crosswalks (especially Medicare’s).

3. Missing or Invalid Diagnosis Code (FL 67)

❌ Error: Invalid ICD-10-CM code, or truncated diagnosis entries

🔎 Impact: DRG grouping failure, medical necessity denial

✅ Fix: Use updated ICD-10 codes and validate with coding software or CCI edits before submission.

4. Incorrect Discharge Status (FL 17 or FL 6X Range)

❌ Error: Reporting “01” (discharged home) when patient was transferred

🔎 Impact: DRG payment error or audit risk

✅ Fix: Ensure the discharge disposition matches patient record and post-acute care plan.

5. Omitted Value, Condition, or Occurrence Codes

❌ Error: Leaving FL 18–41 blank when they apply (e.g., accident, hospice care)

🔎 Impact: Payment delay or rejection due to incomplete claim data

✅ Fix: Review payer billing instructions for codes based on care setting and reason for service.

6. Provider NPI or Taxonomy Code Errors (FL 56, 81)

❌ Error: Submitting an invalid or outdated NPI, or missing taxonomy in FL 81

🔎 Impact: Payer can’t identify the provider; claim rejected

✅ Fix: Always cross-check provider NPI against the NPPES registry and taxonomy code lists.

7. Improper Use of Occurrence Dates

❌ Error: Reporting an incorrect accident or onset date

🔎 Impact: Denied due to untimely filing or incorrect benefit coordination

✅ Fix: Match occurrence codes and dates with clinical documentation (e.g., progress notes, H&P).

8. Using Facility NPI in the Rendering Provider Field

❌ Error: Substituting the facility’s NPI for the attending/operating provider

🔎 Impact: Rejection due to missing attending provider requirement

✅ Fix: Input individual NPI of the attending/operating provider in FL 76–79.

9. Inconsistent Dates of Service Across Fields

❌ Error: FL 6 (Statement Period) doesn’t match revenue line dates in FL 45

🔎 Impact: Suspicion of incorrect billing, audit flag

✅ Fix: Reconcile Statement Covers Period with individual Service Dates.

10. Incorrect Payer Order (Primary vs. Secondary)

❌ Error: Listing Medicare as secondary when it should be primary (or vice versa)

🔎 Impact: Coordination of benefits (COB) rejections

✅ Fix: Follow COB rules and complete FL 50–65 accurately.

🧠 Pro Tips to Minimize UB-04 Errors

✅ Use billing scrubbers or RCM tools with UB-04 edit validation
✅ Train staff on payer-specific UB-04 rules
✅ Monitor remittance advice (RA) for denial trends
✅ Keep coding manuals and NUBC updates current

UB-04 vs. CMS-1500 – Key Differences in Billing Forms

Many providers and billing teams often confuse the UB-04 and CMS-1500 forms. While both are used to submit claims for medical services, they differ in purpose, structure, and usage

What Is the CMS-1500 Form?

The CMS-1500 (also called the HCFA 1500) is the standardized claim form used to bill:

Professional services
Outpatient providers
Independent practitioners (e.g., physicians, therapists, labs)

It is maintained by the National Uniform Claim Committee (NUCC) and is commonly used in private practices, ambulatory surgical centers, and urgent care settings.

What Is the UB-04 Form?

The UB-04 (also known as CMS-1450) is used for institutional billing and maintained by the National Uniform Billing Committee (NUBC). It is the standard form for:

Hospitals
Skilled Nursing Facilities (SNFs)
Rehabilitation centers
Home health agencies
Hospice care

It captures revenue codes, occurrence codes, discharge status, and other fields required for facility-based reimbursement.

UB-04 vs. CMS-1500 – Side-by-Side Comparison Table

Criteria	UB-04 (CMS-1450)	CMS-1500 (HCFA)
Form Used For	Institutional billing (hospitals, SNFs, hospices)	Professional billing (physicians, clinics, labs)
Maintained By	National Uniform Billing Committee (NUBC)	National Uniform Claim Committee (NUCC)
Claim Type	Facility-based claims	Individual or group provider claims
Fields Included	81 Form Locators: revenue codes, condition codes, etc.	33 Fields: NPI, diagnosis, CPT/HCPCS, etc.
Billing Method	UB-04 or 837I (electronic)	CMS-1500 or 837P (electronic)
Typical Payers	Medicare Part A, Medicaid, Commercial plans (facility claims)	Medicare Part B, Medicaid, Commercial plans (provider claims)
Format	Red-ink scannable form with 81 FLs	Red-ink form with 33 fields

UB-04 Billing Guidelines by Payer (Medicare, Medicaid, and Commercial)

Payer-Specific UB-04 Billing Rules & Guidelines

Though the UB-04 is a universal form, each payer (Medicare, Medicaid, private insurers) has distinct policies that affect:

Which fields are mandatory
Acceptable coding formats
Required attachments or documentation
Timeframes for filing

Below is a breakdown of payer-specific UB-04 requirements:

1. Medicare (UB-04 for Medicare Part A)

Form version: CMS-1450 / 837I
Submission methods: Paper or electronic via EDI
Payer ID: Varies by MAC (Medicare Administrative Contractor)

Key UB-04 requirements:

Type of Bill (TOB): Must match care setting (e.g., 111 for inpatient)
FL 42 (Revenue Codes): Required for grouping under DRGs/APCs
FL 67 (Diagnosis Codes): Must use ICD-10-CM format
FL 76–79: NPI of attending and operating physicians
Condition Codes: Use CC 04 for informational-only claims
Occurrence Codes: Required for hospice and accident reporting

🧠 Use CMS’s Medicare Claims Processing Manual for UB-04 guidance by care type.

2. Medicaid

State-specific rules: Each state Medicaid program customizes UB-04 rules

Common requirements:

Enrollment-specific Payer ID and taxonomy codes in FL 81
Revenue Codes often mapped differently than Medicare
Condition and Occurrence Codes used more extensively (e.g., CC 30 for hospice)
Attachments: Consent forms or authorizations may be required
Timely Filing Limits: 90–365 days depending on state

🧠 Always verify with your state’s Medicaid provider manual.

3. Commercial Insurance Payers (Aetna, Cigna, BCBS, UHC, etc.)

Varied rules across carriers: Refer to provider portals or EDI companion guides

General requirements:

FL 50–65: COB (Coordination of Benefits) section must be complete
Prior Authorization Numbers: Often required in FL 63
Accurate Discharge Status: Commercial plans flag errors in FL 17 or FL 6X
Paper Claims: UB-04 form must be printed in red ink on CMS-1450 standard stock
Attachments/Notes: Can be submitted via payer portals (or in FL 80)

🧠 Avoid blanket submissions. Tailor your claim formatting per payer-specific UB-04 edits

4. Secondary Payers (Coordination of Benefits)

If Medicare or a commercial plan is secondary, submit with:

FL 54 (Prior Payments)
FL 60 (Insured’s ID number)
EOB from the primary payer (if required)

5. Timely Filing by Payer (General Guidelines)

Payer	Time Limit to File
Medicare	Within 1 calendar year of DOS
Medicaid	Varies by state (90–365 days)
Aetna/Cigna	Typically 90–180 days
UHC/BCBS	180 days or per contract

Best Practices for Payer-Specific UB-04 Success

✔️ Use payer edit rules in your EHR or billing system

✔️ Keep a UB-04 payer matrix or checklist per carrier

✔️ Run trial claims for high-dollar inpatient admissions

✔️ Monitor RAs/ERAs for payer-specific denial trends

✔️ Stay current with payer newsletters and policy bulletins

UB-04 in Electronic Claim Submission (837I File Format)

What is the 837I Format?

The 837I is the Electronic Data Interchange (EDI) version of the UB-04 form. While UB-04 is the paper format, 837I is the electronic equivalent, used to submit institutional claims digitally to:

Medicare
Medicaid
Commercial payers
Clearinghouses

📌 “I” stands for Institutional — distinguishing it from 837P (Professional) and 837D (Dental) formats.

UB-04 vs. 837I: What’s the Difference?

FeatureUB-04 (CMS-1450)837I EDI FileFormatPaper or PDFElectronic data format (X12 – 005010X223A2)Submission MethodManual or fax/mailThrough clearinghouses or direct EDIStandard UseInstitutional claim billingInstitutional claim billing (automated)Governing BodyNUBCCMS and X12N (HIPAA compliant)✅ While the data captured is almost identical, the 837I offers faster, scalable, and error-resistant processing.

Key Elements of the 837I EDI File

The 837I format contains segments that mirror UB-04 fields. These include:

UB-04 Field	837I Segment	Purpose
FL 1 (Billing Provider Info)	NM1, N3, N4, REF	Identifies billing entity & address
FL 4 (Type of Bill)	CLM05-1	Facility and frequency code
FL 42–47 (Revenue Lines)	SV2	Revenue code, HCPCS, charges
FL 67 (Diagnosis Codes)	HI segment	Principal and secondary ICD-10 codes
FL 76–79 (Provider IDs)	NM1, PRV, REF segments	Attending, operating, rendering providers
FL 50–65 (Payer Info)	SBR, NM1, N3, REF	Subscriber, payer, and insured info

⚙️ EDI files require adherence to ASC X12N 837I Implementation Guide, which includes loop, segment, and element requirements.

How to Submit an 837I Claim

1.Prepare the claim data

Export the UB-04 equivalent data from your EHR or billing software.

2.Map the data to the 837I format

Use middleware or clearinghouse tools to convert it to EDI format.

3.Validate the file

Run the claim through:

HIPAA validation
Payer-specific edits (CIC, NCCI)

4.Submit to a clearinghouse or payer directly

Use secure FTP or direct connections (EDI Gateway).

5.Check for 999 and 277CA responses

These are acknowledgments from the payer for claim receipt and errors.

Benefits of Electronic UB-04 (837I)

📈 Faster reimbursement cycles

🔄 Improved claim tracking & audit trails

🧮 Fewer manual errors and rejections

🔐 HIPAA-compliant and secure

🔍 Supports bulk institutional billing (batch claims)

Tools that Support 837I

Clearinghouses: Availity, Change Healthcare, Office Ally
RCM Software: Kareo, AdvancedMD, eClinicalWorks
EDI Gateways: Ability Network, Optum, Trizetto

Frequently asked questions on ub-04

What is the UB-04 form used for in medical billing?

UB-04, also called CMS-1450, is used to bill institutional claims for services like hospital, SNF, and hospice care under Medicare Part A and other insurers.

Who uses the UB-04 form?

Hospitals, rehab centers, hospices, and nursing homes use the UB-04 to bill facility-based services. Outpatient providers use CMS-1500 instead.

What is the difference between UB-04 and CMS-1500?

UB-04 is for institutional billing; CMS-1500 is for professional billing. They differ in format, fields, and billing use cases.

What are revenue codes on the UB-04?

Revenue codes indicate the type of service or department (e.g., ER, lab) and are essential for payer reimbursement.

What is a Type of Bill (TOB) on the UB-04?

The Type of Bill (TOB) is a 3-digit code that identifies the facility type and billing frequency.

Can I submit a UB-04 electronically?

Yes, UB-04 claims can be submitted electronically using the 837I EDI format through clearinghouses or direct payer connections.

What is the difference between UB-04 and 837I?

UB-04 is the paper form; 837I is its electronic EDI equivalent used for submitting institutional claims digitally.

What are common errors on the UB-04 form?

Common UB-04 errors include wrong revenue codes, invalid diagnosis, incorrect TOB, and missing provider or occurrence codes.

What is Form Locator 67 on the UB-04?

Form Locator 67 contains the principal diagnosis code, which drives reimbursement under DRGs for inpatient claims.

How many fields does the UB-04 form have?

The UB-04 form has 81 Form Locators used to capture patient, provider, service, and billing details.

How is DRG reimbursement linked to the UB-04 form?

Hospitals use UB-04 to report diagnoses and procedures, which group into Diagnosis Related Groups (DRGs). Accurate coding on Form Locators ensures correct Medicare Part A reimbursement.

What are occurrence codes on the UB-04 form?

Occurrence codes capture specific events like accident dates, onset of symptoms, or qualifying stays. Incorrect or missing codes often trigger payer denials or delays.

How do condition codes work on the UB-04?

Condition codes indicate special circumstances, such as billing for hospice, Medicare secondary payer, or outpatient services. They guide payer processing and coverage decisions.

What are value codes on the UB-04?

Value codes report additional payer-relevant amounts, such as patient liability, Medicare deductible, or blood units furnished. Incorrect reporting can cause underpayments.

How does the UB-04 support Medicare crossover claims?

When Medicare pays primary, UB-04 enables automatic crossover of remaining balances to Medicaid or secondary payers. Missing fields can block crossover and delay reimbursement.

What role does UB-04 play in outpatient facility billing?

Though widely used for inpatient, UB-04 is also required for outpatient services at hospitals, SNFs, and rehab centers. Correct revenue and TOB codes ensure payment.

Why do payers reject UB-04 claims for invalid NPI or taxonomy?

Claims require the billing provider’s correct NPI, taxonomy, and facility type. Mismatches between provider enrollment and UB-04 entries often trigger payer rejections.

How does UB-04 interact with Medicare Part A vs Part B?

Part A institutional services (hospital, SNF, hospice) bill via UB-04, while Part B professional services use CMS-1500. Facilities often submit both, depending on service.

What happens if revenue codes don’t match CPT/HCPCS codes on UB-04?

Mismatch between revenue codes and procedure codes is a top denial reason. Payers expect alignment to validate the type and location of service.

Are UB-04 forms required for Medicaid billing?

Yes. Most state Medicaid programs mandate UB-04 for institutional claims. Requirements vary by state, especially for behavioral health and long-term care facilities.

Do behavioral health facilities use UB-04 or CMS-1500?

It depends. Outpatient mental health practices often use CMS-1500, while inpatient or facility-based behavioral health services typically bill with UB-04.

Can UB-04 claims be submitted electronically?

Yes. Most clearinghouses and payers accept UB-04 data electronically in the 837I format, even though paper UB-04 is still widely referenced.

Do all insurance companies accept the UB-04 form?

Yes, but requirements for fields like value codes, condition codes, and revenue codes vary by payer.