UB-04 and CMS-1500: how to read the claim forms behind a medical bill

Both are standard claim forms. A provider fills 1 in, or sends the same data electronically, to ask a payer for money. The difference is who is asking.

The UB-04 is the uniform bill for institutions: hospitals, skilled nursing facilities, home health agencies, hospices and some clinics. Medicare calls it form CMS-1450. The National Uniform Billing Committee (NUBC) maintains its codes. The CMS-1500 is the claim form for professionals: physicians, nurse practitioners, therapists in private practice, ambulance suppliers and most other non-institutional providers. The National Uniform Claim Committee (NUCC) maintains it, and the current version, 02/12, was approved by the Office of Management and Budget on June 10, 2013.

So a 3-day hospital stay after a car crash usually produces 1 UB-04 from the hospital, plus a CMS-1500 from the emergency physician, 1 from the radiologist who read the scans, 1 from the surgeon, 1 from the anesthesiologist and more. Each bills separately, on a different form, with different codes. A reviewer who has only the hospital bill has not seen what the doctors charged.

Most claims today go electronically. The Administrative Simplification Compliance Act requires Medicare claims to be sent electronically unless an exception applies; for small providers the rule at 42 CFR 424.32(d) sets the cut-off at fewer than 25 full-time equivalent employees for providers of services and fewer than 10 for physicians, practitioners, facilities and suppliers. The electronic formats are the X12 837 transactions, version 5010: 837I for institutional claims and 837P for professional claims. The paper forms still matter because every electronic claim maps to their boxes, and billing records produced in litigation usually print in their layout.

Terms you will meet

Form locator (FL)

A numbered box on the UB-04. FL 42 is the revenue code column, FL 67 the principal diagnosis.

Item

A numbered box on the CMS-1500. Item 21 holds diagnoses; item 24 holds service lines.

Revenue code

A 4-digit NUBC code for the department or type of charge on a UB-04 line, such as 0450 for the emergency room.

HCPCS and CPT

Codes for procedures and services. CPT codes are the level I HCPCS codes. They appear on both forms.

ICD-10-CM and ICD-10-PCS

Diagnosis codes (CM) on both forms, and inpatient procedure codes (PCS) on the UB-04 only.

POA indicator

A letter next to each inpatient diagnosis showing whether the condition was present when the patient was admitted.

Type of bill (TOB)

A 4-digit UB-04 code that says what kind of facility billed, for what kind of care, and whether the claim is an original or a correction.

Itemized bill

A line-by-line list of every charge, often with the hospital's internal charge codes. It carries more detail than the claim form and is a separate request.

The mock UB-04 below shows the boxes that matter most in a claim review. The real form has 81 form locators; the layout here is simplified and the entries are invented.

Other boxes worth reading

The CMS-1500 is shorter and carries 1 professional's services. The top half is about the patient, the insurance and the injury. The bottom half is the service lines.

Place of service codes you will see

Item 24B tells you where each service happened. The same CPT code can be paid differently in an office and in a hospital, and the code is a quick check against the chart.

How the 2 forms compare

Most of each form is codes. 5 code sets do most of the work, and knowing which is which saves hours.

Revenue codes that show up in injury files

Discharge status and POA codes

Discharge status (FL 17) tells you where the patient went: 01 home or self care, 02 another short-term hospital, 03 skilled nursing facility, 06 home with home health services, 07 left against medical advice, 20 expired, 62 inpatient rehabilitation facility, 63 long-term care hospital. Each one other than home points to another record to request.

POA indicators sit beside each inpatient diagnosis:

Present on admission means present when the inpatient admission order was written. A condition that develops in the emergency department, in observation or during outpatient surgery before the order counts as present on admission.

Claim forms are governed by payer rules, HIPAA transaction standards and, for hospitals, price transparency rules. 5 of them matter most to someone reading bills after the fact.

Billed charges are not what was paid

The price transparency rule at 45 CFR 180.20 defines a gross charge as the charge for an item or service reflected on a hospital's chargemaster, absent any discounts. That is usually the number on a UB-04. Payers then pay a negotiated or fee-schedule amount, and the difference is written off or, in some cases, billed to the patient. The same regulation defines the discounted cash price and the payer-specific negotiated charge. Which number counts as a medical special is a question of state law, and our guide to medical billing review covers how reviewers handle it.

Present on admission and hospital-acquired conditions

The Deficit Reduction Act of 2005 told CMS to stop paying hospitals more for certain conditions that the patient acquired in the hospital. For inpatient discharges on or after October 1, 2007, hospitals paid under the inpatient prospective payment system (IPPS) report a POA indicator on the principal and every secondary diagnosis. When a selected hospital-acquired condition was not present on admission, the hospital does not get the higher payment that condition would otherwise bring.

The selected conditions include foreign objects retained after surgery, air embolism, blood incompatibility, stage III and IV pressure ulcers, falls and trauma, catheter-associated urinary tract infections, vascular catheter-associated infections, manifestations of poor glycemic control, certain surgical site infections, and deep vein thrombosis or pulmonary embolism after certain orthopedic procedures. In a negligence claim, an "N" beside 1 of those diagnoses is the hospital's own coder recording that the condition started during the stay. It is a coding judgment made from the chart, not a finding of fault, but it tells you where to read.

What each flag means

1. Discharge status 01 against a transfer to a skilled nursing facility. The chart says the patient went to a facility; the bill says home. The status code affects how some payers pay, and it also means the skilled nursing records may not be in the file yet.
2. 2 CT units, 1 report. There may be a second scan (a head or chest CT on arrival is common after a crash), or a duplicate charge. Check the radiology log and the itemized bill line.
3. 2 units of PT evaluation, 1 note. Same question. Either a second evaluation is missing from the file or the units are wrong.
4. Blood loss anemia coded as not present on admission. The drop in hemoglobin after surgery supports the coder's call. In this case it is expected after a femur fixation and is not a hospital-acquired condition on the CMS list; it still belongs in the chronology as a post-operative event.
5. "Auto accident: No" from the emergency physician. A wrong box can send the claim to the health insurer instead of the auto carrier and affect liens and subrogation. Ask for the corrected claim if there is 1.
6. A clinic visit billed with no note. The bill proves a visit was billed. The records request should name the date.

The same stay on 1 timeline

The method works for 1 emergency visit or 2 years of treatment. Build the list of providers from the bills and the list of events from the chart, then match them.

1. Request billing records with the chart. UB-04s, CMS-1500s, itemized bills, EOBs and payment ledgers from every provider. Billing records sit in the designated record set.
2. List every bill. 1 line per claim form: provider, form type, type of bill or place of service, dates, total charge, page.
3. Remove duplicates. The same claim often arrives from the provider, the patient and the insurer. Corrected claims (frequency 7) replace originals; voids (8) cancel them.
4. Build the provider list from the bills. Every NPI in the attending, operating, referring, rendering and billing boxes is a possible source of records.
5. Match each service line to a chart page. Date, place, code and units against the note, report or order.
6. Check the injury fields. Item 10, item 14, occurrence codes and remarks against the incident date and facts.
7. Read diagnoses and POA flags. Pre-existing conditions coded on arrival, and conditions coded as arising during the stay.
8. Total from lines, not statements. Keep billed, paid and adjusted amounts in separate columns.

Does this bill line belong in the specials?

BILL-TO-RECORD RECONCILIATION LOG
Patient: [ID]    Incident date: [DATE]    Prepared by: [NAME]

Bill page | Provider | Form (UB-04 / CMS-1500) | TOB or POS
          | Date of service | Revenue or CPT/HCPCS code | Units | Billed charge
          | Diagnosis (code, POA if inpatient)
          | Chart page for the same date and service (or NONE)
          | Match? (yes / units differ / code differs / no record)
          | Duplicate or corrected claim? (page of the other copy)
          | Question

Example:
p. 401 | County Hospital | UB-04 | 0111
       | 03/02 | 0350 CT | 2 | [amount]
       | S72.301A, POA Y
       | p. 88 (1 CT report)
       | Units differ
       | None found
       | Second CT, or duplicate? Request radiology log

BILLING RECORDS REQUEST
Patient: [NAME]    Date of birth: [DATE]
Dates of service: [FROM] to [TO]

Please produce, for these dates:
1. All claim forms submitted to any payer (UB-04 / CMS-1450 and
   CMS-1500), including original, corrected (frequency 7) and
   voided (frequency 8) claims.
2. The itemized statement of charges, with charge codes,
   descriptions, dates, units and amounts.
3. Explanations of benefits and remittance advice received,
   and the payment and adjustment ledger for the account.
4. Any liens, letters of protection or assignments of benefits.
5. The name and NPI of every physician or group that billed
   separately for services during these dates.

Billing records are part of the designated record set
(45 CFR 164.501). Electronic copies are preferred.

Before you total the specials

• Both forms from every stay are in handThe facility UB-04 and a CMS-1500 from each professional who billed.
• Duplicates are removedProvider, patient and insurer copies of the same claim count once.
• Corrected and voided claims are sortedFrequency 7 replaces, 8 cancels.
• Every line has a chart page or a requestNo billed service without a record or a follow-up.
• Injury fields match the incidentItem 10, item 14, occurrence codes and remarks.
• Billed, paid and adjusted are separate columnsSo the total can follow whatever rule your jurisdiction uses.

0 of 6 checked.

For liens and deferred-payment bills, see our guide to medical liens and letters of protection. For removing duplicate pages before you start, see deduplicating medical records for personal injury. Pharmacy lines are checked against the medication administration record, and physician visit lines against the progress notes.

Bill review is matching work at volume. A serious injury case can hold hundreds of claim forms, itemized bills and EOBs, many of them duplicates, spread across thousands of pages of records. Chapter 7's method is the same for 10 bills or 1,000. What changes is the time.

AI medical record review handles the matching well when every output is tied to a page. A grounded system can read each bill, list its lines, group them by provider and date, find the same claim sent 3 times, and place each billed date on the same timeline as the clinical events, so the gaps show. It can also flag a billed date with no matching record. That turns a billing file into part of an AI medical chronology instead of a separate spreadsheet.

The limits are the usual ones. A large language model (LLM) that summarizes bills without citations can produce a total that no page supports; hallucination is why every figure needs a page-level citation back to the line it came from. Scanned bills need OCR, and handwritten entries on older paper ledgers are harder for any system. Codes are easy to read and easy to misread: an ICD-10 code on a bill is a coding judgment, not a clinical finding. The human in the loop decides which charges belong in a claim and what they are worth.

Medrecords AI works this way on the files you upload. The claims billing ledger lists every billed line with its source page, the billing summary rolls them up by provider, date or category with every total cited, and bill review compares each billed line with UCR and geographic benchmark data and shows where it falls. Billed dates sit on the same cited medical chronology as the care, pages go through OCR matched to their content, including handwritten entries, and you can ask "every charge on 03/02 with the record that supports it" through cited Q&A and record search. It flags records that should exist but were not produced. Flags are signals, not verdicts. It does not reprice or reduce a bill, decide what a charge is worth, or retrieve records from providers. It runs under SOC 2 and HIPAA with a signed business associate agreement (see security and HIPAA). Self-Service bills 10 cents a deduplicated page, down to 5 cents at volume, duplicates free; Enterprise On-Prem is an annual license.

If you are comparing tools, our guide to medical record review covers what to ask any medical chronology software vendor. See how bill review fits personal injury, medical special damages, lien resolution and workers' compensation work.

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

The UB-04 (CMS-1450) is for institutions such as hospitals, skilled nursing facilities and home health agencies. The CMS-1500 is for physicians and other professionals. A hospital stay usually produces 1 UB-04 plus a CMS-1500 from each doctor who billed separately.

Is the UB-04 the same as the CMS-1450?

Yes. CMS-1450 is Medicare's name for the UB-04 uniform bill. The National Uniform Billing Committee maintains its codes.

What is a type of bill code?

A 4-digit code in form locator 4 of the UB-04. After a leading 0 come the facility type, the bill classification and the frequency. 0111 is a hospital inpatient claim from admission through discharge.

What is a revenue code on a hospital bill?

A 4-digit NUBC code in form locator 42 that names the department or type of charge, such as 0450 for the emergency room or 0360 for the operating room. Revenue code 0001 is the total line.

What does POA mean on a UB-04?

Present on admission. Each inpatient diagnosis carries Y, N, U, W or 1 to say whether the condition was present when the inpatient admission order was written. Conditions that arose in the emergency department before the order count as present.

Are billing records part of the medical record?

Under HIPAA, billing records are part of the designated record set, the records a patient has a right to access. Many providers keep and produce them separately from the chart, so request them by name.

Why do the bill and the chart show different diagnoses?

Coders assign codes from the documentation after the fact, under coding rules, and a bill may list only the diagnoses that support its charges. A difference is a reason to read the chart, not proof of an error.

How do you find missing records from medical bills?

List every provider NPI and date of service on the bills, then look for a chart page for each. A billed date with no record is a request to send. A discharge status other than home points to another facility's records.

Can AI read UB-04 and CMS-1500 forms?

It can read the lines on scanned or printed claim forms and itemized bills, group them, find duplicates and cite each figure to its page. Whether a charge belongs in a claim, and what it is worth, stays a human decision.

Is it HIPAA compliant to upload medical bills to an AI tool?

It can be, with a vendor that signs a business associate agreement, holds a SOC 2 report and commits in writing not to train on your data. Bills carry the same protected health information as the chart.

CMS manuals and regulations were read in full text from primary sources in September 2026, and quoted text is verbatim. Code meanings come from CMS manuals and CMS Blue Button code definitions. The mock forms, patient, providers, dates, codes and pages in chapters 2, 3, 6 and 7 are hypothetical. Product facts come from this site's product pages. Nothing here is legal, billing or medical advice.

• CMS Medicare Claims Processing Manual, chapter 25, Completing and Processing the Form CMS-1450 Data Set (Rev. 12423, December 20, 2023): form locators, type of bill, revenue code order, principal and admitting diagnosis definitions, 450-line claims, FL 80 remarks.
• CMS Medicare Claims Processing Manual, chapter 26, Completing and Processing Form CMS-1500 Data Set (Rev. 12779, August 9, 2024): NUCC, version 02/12 approval, items 10 to 33, 12 diagnosis codes, 6 service lines, place of service.
• 42 CFR 424.32 and 424.44: claim forms, electronic submission and small-provider thresholds, 1-year filing limit.
• 45 CFR 162.1102: X12 837 version 5010 for health care claims.
• 45 CFR 164.501: the designated record set includes billing records.
• 45 CFR 180.20 and 180.50: gross charge and other standard charge definitions; hospital charge list requirements.
• CMS, Hospital-Acquired Conditions and Present on Admission Indicator Reporting Provision (ICN 901046): POA indicators, October 1, 2007 start, selected conditions, exempt hospitals.
• CMS Blue Button code definitions: revenue codes, discharge status, facility type, claim classification, frequency, POA and place of service values.
• National Uniform Billing Committee and National Uniform Claim Committee: the bodies that maintain the UB-04 codes and the CMS-1500.