UB04 Field 4: Type of Bill

Overview

Field Locator 4 (FL 4), titled Type of Bill (TOB), is a critical four-digit code that identifies the specific type of facility, the classification of care, and the sequence of the claim within a patient's episode of care. Located in the upper right-hand corner of the UB-04 claim form, this field acts as the primary "map" for payer adjudication systems. It dictates which reimbursement methodology applies, such as Inpatient Prospective Payment System (IPPS) or Outpatient Prospective Payment System (OPPS).

The code is structured into four positions, though the first digit is a leading zero (often ignored by some legacy systems but required for HIPAA-compliant 837I electronic transactions). The second digit defines the Type of Facility (e.g., Hospital, Skilled Nursing), the third digit defines the Bill Classification (e.g., Inpatient, Outpatient), and the fourth digit defines the Frequency of the report (e.g., Admit through Discharge, Interim). According to CMS Pub. 100-04 Chapter 25, accurate TOB reporting is mandatory for all institutional providers to ensure proper claim routing and benefit period tracking.

When to Use This Field

Institutional providers must use Field 4 on every UB-04 submission to establish the "billing logic" for the claim. This field is used to distinguish between a one-time service and a long-term stay that requires multiple billings.

Scenario 1: Acute Care Discharge A patient is admitted to an acute care hospital for a three-day appendectomy and is discharged home. The biller must use TOB 0111 (Hospital Inpatient, Admit through Discharge). This tells the payer that the entire stay is encapsulated in this single claim and no further interim bills are expected for this encounter.

Scenario 2: Long-Term Skilled Nursing Stay A patient resides in a Skilled Nursing Facility (SNF) for 60 days. Because SNFs typically bill monthly, the biller uses TOB 0212 (SNF Inpatient, Interim - First Claim) for the first 30 days. The subsequent month is billed with TOB 0213 (Interim - Continuing Claim). This sequence allows the payer to track the utilization of the patient's 100-day Medicare SNF benefit CMS Medicare Claims Processing Manual.

Step-by-Step Claim Example

Patient Scenario: A 70-year-old Medicare beneficiary is admitted to an acute care hospital on October 1st for a hip replacement. The patient is stable and discharged to a rehabilitation center on October 4th.

1. Identify Facility Type: The facility is an acute care hospital, which corresponds to the second digit 1.
2. Identify Classification: The patient was admitted as an inpatient, which corresponds to the third digit 1.
3. Identify Frequency: The patient was admitted and discharged within the same billing period. This is a single, complete claim, which corresponds to the fourth digit 1.
4. Enter Value in FL 4: The biller enters 0111.
5. Supporting Data: The biller ensures Field 6: Statement Covers Period matches the admission and discharge dates (10/01 – 10/04).
6. Payer Response: The Medicare Administrative Contractor (MAC) receives the 837I transaction. The 0111 TOB triggers the MS-DRG grouper. The payer verifies that no other inpatient claims exist for these dates. If the biller had mistakenly used 0112, the payer would "suspend" the claim, waiting for a 0114 (Last Claim) to arrive before finalizing payment.

Common Mistakes & Audit Red Flags

• Frequency Mismatches: Using TOB 0111 when the patient is still in the facility is a frequent error. If a patient remains in-house, but the hospital needs to bill for a partial stay to maintain cash flow, they must use 0112 (Interim - First). Submitting a 0111 while the patient is still admitted will cause a "duplicate claim" or "overlap" denial when the next claim is submitted.
• Incorrect Replacement Codes: When correcting a previously denied or underpaid claim, billers often submit a new original claim instead of using Frequency Code 7 (Replacement of Prior Claim). For example, TOB 0137 must be used to replace a previously processed outpatient claim. Failure to use the "7" frequency code results in denials for "Duplicate Service" NUBC Official UB-04 Data Specifications.
• Newborn Source Inconsistency: Using TOB 0111 with a Newborn Admission Type 4 requires specific Newborn Admission Source codes in Field 15: Point of Origin. Mismatches between the TOB and the Admission Type trigger immediate front-end edits.

Related Codes & Fields

Related UB-04 Fields

• Field 6: Statement Covers Period
• Field 12: Admission Date
• Field 15: Point of Origin
• Field 17: Patient Discharge Status

Child Codes for Field 4

• 0111: Hospital Inpatient - Admit through Discharge
• 0112: Hospital Inpatient - Interim - First Claim
• 0113: Hospital Inpatient - Interim - Continuing Claim
• 0114: Hospital Inpatient - Interim - Last Claim
• 0117: Hospital Inpatient - Replacement of Prior Claim
• 0118: Hospital Inpatient - Void/Cancel of Prior Claim
• 0121: Hospital Inpatient (Part B Only)
• 0131: Hospital Outpatient - Admit through Discharge
• 0137: Hospital Outpatient - Replacement of Prior Claim
• 0211: Skilled Nursing Inpatient (Part A)
• 0321: Home Health Inpatient (Plan of Care)
• 0831: Specialty Facility - Ambulatory Surgery Center
• 0851: Specialty Facility - Critical Access Hospital

References

1. CMS Pub. 100-04 Chapter 25
2. CMS Medicare Claims Processing Manual
3. NUBC Official UB-04 Data Specifications