5.3 The UB-04 Institutional Claim and Revenue Codes
Key Takeaways
- The CMS-1450, also called the UB-04, is the paper institutional claim; the 837I is the HIPAA electronic institutional claim. Hospitals, including hospital outpatient departments, use this family of claims.
- Hospital outpatient facility services are billed with type of bill 13X (four characters with a leading zero on the form, such as 0131). Inpatient hospital is 11X; inpatient Part B is 12X; non-patient laboratory specimens use 14X; critical access hospitals commonly use 85X.
- Effective January 1, 2008, Medicare no longer processes type of bill 83X for ambulatory surgical centers; ASCs submit the 837P or CMS-1500 with place of service 24. Hospital outpatient surgery after August 1, 2000 is reported on 13X, not as a routine 83X.
- Form Locator 42 holds NUBC revenue codes, the chargemaster language of the facility claim. Lines are listed in ascending revenue-code order, paired with HCPCS in FL 44 on outpatient claims, and 0001 is the hard-copy total line.
- Condition, occurrence, and value codes (FL 18–28, 31–36, and 39–41) carry MSP, accident, and other processing facts; they are not optional decoration on a clean outpatient bill.
The Certified Outpatient Coder exam is a facility outpatient exam. The claim that carries hospital chargemaster language is the institutional claim. CMS calls the paper form the CMS-1450. The industry still calls it the UB-04. The electronic HIPAA transaction is the 837I (institutional), currently Version 5010A2. MLN006926 (December 2025) is CMS's booklet for this pair. The National Uniform Billing Committee (NUBC) maintains the code lists used on the form: type of bill, revenue codes, condition codes, occurrence codes, occurrence span codes, value codes, point of origin, discharge status, and related institutional values. Medicare completion rules live in the Medicare Claims Processing Manual, Chapter 25. This OpenExamPrep section teaches those CMS and NUBC ideas for COC study. It is not a substitute for a current NUBC Official UB-04 Data Specifications Manual subscription, and it is not an AAPC workbook.
Paper CMS-1450 claims are the exception. ASCA requires electronic claims unless a waiver or exception applies. Small institutional providers with fewer than 25 full-time equivalent employees who bill their MAC are one exception. Roster billing for certain immunizations, demonstration-project paper claims, and certain multi-primary MSP claims are others. Medicare Fee-for-Service institutional claims go to the A/B MAC for the state where the services were provided. Medicare Advantage institutional claims go to the MA plan. File Medicare claims no later than one calendar year after the date of service; a timely-filing denial is not an appealable initial determination.
Type of bill: why 13X is the hospital outpatient default
Form Locator 4 is type of bill (TOB). On the form it is four characters. CMS manuals often write the family as 13X, meaning a leading zero plus facility type 1 (hospital) plus classification 3 (outpatient) plus a frequency digit. The frequency digit is an NUBC value that distinguishes a complete admit-through-discharge outpatient bill from a replacement or a void. Common frequencies used in Medicare processing include a complete bill, a replacement of a prior claim, and a void/cancel. Always use the current NUBC frequency list rather than inventing a fourth digit.
| TOB family | What it is on a hospital claim | COC use |
|---|---|---|
| 11X | Hospital inpatient | Part A inpatient facility; not the usual hospital outpatient surgery claim |
| 12X | Hospital inpatient Part B | Ancillary Part B services in defined inpatient Part B situations |
| 13X | Hospital outpatient | Default for HOPD, ED, hospital outpatient surgery, observation, and hospital clinics subject to OPPS (with published exceptions such as Maryland, IHS, and CAHs) |
| 14X | Hospital other Part B / non-patient | Effective April 1, 2006, 14X is for non-patient laboratory specimens |
| 85X | Critical access hospital | CAH outpatient institutional billing |
| 83X | Historically labeled ambulatory surgical center / certain outpatient surgery | Not the current Medicare path for freestanding ASC facility claims |
CMS Claims Processing Manual Chapter 4 states that hospitals use the 837I or CMS-1450 to bill covered outpatient services and lists types of bill 13X or 83X, and 85X, in older general outpatient-hospital billing language. The same manual and related transmittals then draw the line that matters on the exam: for dates of service on or after January 1, 2008, the A/B MAC (A) no longer processes claims on TOB 83X for ASCs. All ASC providers, including Indian Health Service ASC providers, must submit those claims to the designated A/B MAC (B) on the professional claim format. For other hospitals, outpatient surgery that had been subject to the old ASC payment limit was reported on 83X before August 1, 2000 and on 13X for surgeries on and after August 1, 2000. Indian Health Service hospitals are the published remaining 83X surgery billing example in that history. If a question asks about a typical 2026 hospital outpatient department, the facility TOB is 13X. If it asks about a Medicare-participating freestanding ASC facility claim, the answer is the CMS-1500 / 837P with place of service 24, not a UB-04 83X in current processing.
OPPS generally applies to hospital outpatient Part B bills in the 12X, 13X, and 14X families, with published exceptions (Maryland, IHS, CAHs, and certain territorial hospitals). How OPPS groups those 13X lines into APCs is the next chapter. This chapter stops at sending the right institutional claim with the right revenue and HCPCS map.
Form locators the outpatient coder actually uses
Chapter 25 walks the form locator by form locator. A COC candidate does not need every inpatient accommodation quirk, but the outpatient charge strip is daily work.
| Form locator | Name | Outpatient facility meaning |
|---|---|---|
| FL 4 | Type of bill | 13X family for hospital outpatient |
| FL 6 | Statement covers period | From and through dates for the bill |
| FL 18–28 | Condition codes | MSP, accident, and other claim-level conditions |
| FL 31–34 | Occurrence codes and dates | Accident, retirement, denial, and similar dated events |
| FL 35–36 | Occurrence span codes | From/through spans when NUBC requires a range |
| FL 39–41 | Value codes and amounts | MSP amounts and other monetary flags; list value codes in ascending order |
| FL 42 | Revenue code | Chargemaster department or accommodation; required on every charge line |
| FL 43 | Revenue description | Narrative or abbreviation; NDC reporting for rebate drugs uses this line when required |
| FL 44 | HCPCS / rates / HIPPS | Outpatient procedure, service, or supply HCPCS; up to four modifiers |
| FL 45 | Service date | Line-item date of service (LIDOS) required on hospital outpatient bills |
| FL 46 | Units | Times the HCPCS was performed, or other unit definition for that revenue |
| FL 47 | Total charges | Charge for that revenue/HCPCS line |
| FL 48 | Noncovered charges | Related noncovered amount, including many self-administered drugs not covered by Part A or B |
| FL 50–54 | Payer, insured, prior payments | Primary/secondary/tertiary payer identification and amounts already paid |
| FL 56 | Billing provider NPI | Hospital NPI |
| FL 67 | Principal diagnosis | ICD-10-CM; do not place periods in the code |
Chapter 25 requires a line-item date of service for every iteration of every revenue code on outpatient bills, including TOB 013X. If the same service occurs on five dates, the revenue code and HCPCS appear five times, once per date. That HIPAA line-item date rule is why a week of hospital outpatient therapy cannot hide on one undated revenue lump.
FL 42 revenue codes: the facility chargemaster language
Professional claims do not use revenue codes. Institutional claims do. CMS Chapter 25, section 75.4, says the provider must enter the appropriate numeric revenue code in FL 42 to explain each charge in FL 47. There is no fixed Total line: the provider enters revenue code 0001 and the adjacent FL 47 amount is the sum of billed charges. List revenue codes in ascending numeric sequence and do not repeat them on the same bill to the extent possible. CMS even tells providers to sum at the zero level when they can, to limit line count, but outpatient HCPCS-required services still need the HCPCS and the line-item date. Hard-copy claims may run to multiple pages; CMS accepts up to 450 lines (up to nine pages on paper).
Revenue codes are four digits. NUBC owns the official list. Subcategories under a family can change, and hospitals map their chargemaster to the current NUBC value, so this guide teaches families rather than pretending every fourth digit is frozen. Families a hospital outpatient coder sees constantly include:
| Family (examples) | Typical hospital outpatient meaning |
|---|---|
| 0250 | Pharmacy, general classification |
| 0270 | Medical/surgical supplies |
| 0320 | Radiology — diagnostic |
| 0360 | Operating room services |
| 0450 | Emergency room |
| 0490 | Ambulatory surgical care |
| 0730 | EKG/ECG |
A same-day surgery claim might show 0360 for the OR, 0270 for supplies, 0250 for drugs, and 0320 if intraoperative imaging is separately identified in the chargemaster. An ED visit uses 0450 as the emergency-department family, often with pharmacy, supply, radiology, and EKG lines beneath it. 0490 is the ambulatory surgical care family on an institutional claim; it is chargemaster language for that service category, not proof that a freestanding ASC should file a UB-04. Exact codes such as 0361 versus 0360 are NUBC subcategory choices. If an exam item shows a four-digit revenue code you do not recognize, reason from the family (first three digits) rather than inventing a subcategory.
FL 44 is where outpatient HCPCS live. Chapter 25 says that when coding HCPCS for outpatient services, the provider enters the HCPCS describing the procedure in FL 44. The form accommodates up to four modifiers, two characters each. CMS points hospitals to the CPT appendix of modifiers approved for ambulatory surgery center hospital outpatient use rather than inventing a hospital-only modifier list. HIPPS rate codes in FL 44 are a SNF/home-health inpatient-style construct, not the usual HOPD surgery pattern.
FL 48 is where noncovered charges sit next to the related revenue code. Self-administered drugs that are not covered under Part A or Part B belong there so they are not processed as covered outpatient drugs. Units in FL 46, when HCPCS are required, equal the number of times the procedure or service was performed.
Condition, occurrence, and value codes at a high level
FL 18–28 hold condition codes. FL 31–34 hold occurrence codes and dates. FL 35–36 hold occurrence span codes. FL 39–41 hold value codes and amounts. CMS requires value codes to be shown in ascending numeric sequence when more than one applies. Negative amounts are not allowed except in FL 41. These fields are how a 13X claim says the visit was an auto accident, that the patient is in an ESRD coordination period, or that a working-aged GHP paid a stated amount. They are the institutional counterpart to MSP loops on the professional claim. Discharge status (FL 17) still appears on outpatient hospital bills; it is not only an inpatient field.
Principal diagnosis in FL 67 is ICD-10-CM. Outpatient procedure coding on this claim is HCPCS in FL 44, not ICD-10-PCS. ICD-10-PCS remains the inpatient facility procedure set.
Outpatient-hospital scenario
A patient is registered in the ED, receives an EKG and a chest X-ray, and then goes to the hospital outpatient OR the same day for an appendectomy without an inpatient admission. The facility claim is TOB 13X. Revenue lines in ascending order might include 0250 pharmacy, 0270 supplies, 0320 diagnostic radiology, 0360 OR, 0450 ED, and 0730 EKG, each with a HCPCS where outpatient HCPCS is required, a line-item date, units, and charges. The 0001 line totals the charges on a paper UB-04. If the appendectomy had instead been performed in a freestanding Medicare ASC, that facility would not build this 13X revenue map for Medicare; it would use the professional claim format with place of service 24. If the patient had been admitted as an inpatient before surgery, the hospital's facility claim would leave the 13X outpatient path and move to inpatient TOB 11X and Part A, which is a different payment system (IPPS) reserved for later in this domain.
Hospital outpatient facility services to a registered hospital outpatient are billed on the institutional claim using which type of bill family?
On the UB-04, Form Locator 42 is used to report:
Which statement about type of bill 83X and ASC facility billing is correct under current CMS claims processing rules?