CMS-1500 vs UB-04: Which Claim Form Do You Use?
Use the UB-04 (CMS-1450, electronic 837I) when you bill as an institution, such as a hospital, and use the CMS-1500 (electronic 837P) when you bill as a physician or other professional. One emergency visit usually produces both claims, one from the facility and one from the physician group.
Written by Salman Saeed, CEO and Co-Founder · Reviewed by a Certified Medical Coder · Last reviewed October 2026In short: the CMS-1500 and UB-04 are not interchangeable. The NUCC maintains the CMS-1500 for professional and supplier claims, the NUBC maintains the UB-04 for institutional claims, and each has its own electronic version, field set and place-of-service logic. A claim on the wrong form is returned as invalid, so it never starts the payer's clock.
Which Claim Form Goes with Which Provider?
The form follows the type of provider billing, not the type of service. CMS booklet MLN006976 calls the CMS-1500 the standard paper claim for non-institutional providers and suppliers, and MLN006926 calls the CMS-1450, also known as the UB-04, the standard paper claim for institutional providers.
Both lists come from the CMS booklets. A few provider types, such as rural emergency hospitals and opioid treatment programs, appear on both. Your enrollment type and the service decide which claim applies, so confirm with your MAC or the payer.
What Is the Difference Between the CMS-1500 and the UB-04?
Both forms feed the same X12 837 family, but the two transactions use different implementation guides and capture different data. Claims Processing Manual Chapter 24 lists the current versions as 005010X222A1 for the professional claim and 005010X223A2 for the institutional claim.
| Item | CMS-1500 and 837P | UB-04 and 837I |
|---|---|---|
| Bills as | Physician, practitioner or supplier | Hospital or other institution |
| Form owner | NUCC designs and maintains the form | NUBC maintains the code lists |
| Medicare instructions | Claims Processing Manual Chapter 26 | Claims Processing Manual Chapter 25 |
| Service line | Item 24, six lines, HCPCS or CPT in 24D with up to four modifiers | FL 42 revenue code with FL 44 HCPCS and FL 45 date, up to 450 lines |
| Setting | Place of service in item 24B | Bill type in FL 4 and revenue code in FL 42 |
| Diagnosis | Item 21, pointer letter A to L in 24E | Principal diagnosis in FL 67, others in 67A and up |
| Billing provider NPI | Item 33a | FL 56 |
| Timely filing date | The From date on the claim | The Through date when the claim has span dates |
Chapter 25 says the UB-04 claim can run to 450 lines, which is nine pages on paper. Item 24 of the CMS-1500 has six service lines. The place of service code on the CMS-1500 and the bill type on the UB-04 do different jobs, so a facility claim never carries a POS code the way a professional claim does.
How Do the Payer, Authorization and Signature Fields Differ?
The UB-04 carries payer, authorization and visit-reason data in form locators 50 to 70, while the CMS-1500 carries insured, signature and provider-signature data in items 4 to 13 and 25 to 31. The two forms ask for the same facts in different places, so a front-end edit written for one will not catch the other.
| Fact | UB-04 location | CMS-1500 location | What Chapter 25 or 26 says |
|---|---|---|---|
| Patient account number | FL 3a | Item 26 | FL 3a is required. Item 26 is optional and the number is returned to the provider. |
| Payer | FL 50 line A | Item 11 | On the UB-04, enter Medicare on line A only when you have developed for other insurance and Medicare is primary. Item 11 must be completed on every Medicare claim. |
| Authorization or referral | FL 63 | Items 17 and 23 | FL 63 is situational and required when the payer assigned an authorization or referral number. Item 17 holds the referring or ordering physician, and item 23 holds a QIO prior authorization number. |
| Reason for the visit | FL 70 | Not used | FL 70 is required on bill types 013x and 085x when FL 14 reports code 1, 2 or 5 and a revenue code of 045x, 0516 or 0762 is reported. |
| Patient or provider signature | Not used by Medicare (FL 53 is ignored) | Items 12, 13 and 31 | Item 12 is the patient's signature and date unless the signature is on file. Item 13 holds the patient's signature or the statement signature on file. Item 31 holds the signature of the provider or supplier and the date. |
| Total charges | FL 47 line 0001 | Item 28 | Item 28 is the total of all charges in item 24F. On the UB-04 the last revenue code line, 0001, carries the sum. |
| Patient paid | Not a separate field | Item 29 | Item 29 is the total amount the patient paid on covered services only. |
The values are made up. They show where each fact lands on each form.
Does One ER Visit Produce Two Claims?
Yes, in most cases. The hospital bills its facility charges on the UB-04, and the emergency physician group bills the physician's work on the CMS-1500. Both claims describe the same patient, date and diagnosis, but each carries different codes.
The numbers below are made up for illustration.
The facility side uses revenue code 0450 and the emergency visit codes such as CPT 99285. The physician group keeps its own pricing and its own denials. Chapter 26, section 10.5 says a physician seeing a registered ER patient may report POS 23.
Are There Cases Where One Claim Covers Both?
Yes. Chapter 25 describes a combined claim that carries both facility and professional components, and gives a critical access hospital claim and a Medicaid clinic bill as examples. On the UB-04 the rendering provider goes in FL 78 or 79 with qualifier 82 when state or federal rules call for a combined claim.
Critical access hospitals paid under Method II report professional fees on the UB-04 with revenue code 0981 and the other 096x and 097x lines, using bill type 085x. Our revenue code 0981 page covers that arrangement. Outside these cases, keep the two claim types separate.
Hospital outpatient departments also trigger a second look at who is paid what. Site-neutral payment explains why the setting changes the facility payment, and place of service codes explains what the physician reports.
What Happens If You Send the Wrong Form?
Medicare treats a submission that does not conform to required claim formats as invalid. Chapter 1, section 70.2.3.1 says incomplete or invalid submissions are returned to the provider, and that they are not considered claims under Medicare regulation. There is no remittance advice for them, so there is nothing to appeal.
Commercial payers vary. A clearinghouse may reject the file before it reaches the payer, or the payer may deny the claim. The denial codes to expect are CO-16, claim lacks information or has a submission or billing error, and CO-5, procedure code or type of bill inconsistent with the place of service. See our pages on CO-16 and CO-5 for the X12 wording.
The fix is to resubmit on the correct form with the same data, inside the payer's filing window. Medicare's window is one calendar year from the date of service, per MLN006926 and MLN006976, so a few weeks lost to a wrong form rarely matters. A payer with a shorter window may not forgive the delay.
Can You Still Send Paper?
Only if you meet an exception. Both MLN booklets say initial Medicare claims go in electronically unless you qualify under the Administrative Simplification Compliance Act. The size test differs by form: fewer than 10 full-time equivalent employees for the CMS-1500, and fewer than 25 for the UB-04.
Both booklets say not to send a printed copy of the form, because the system reads the form colors. For the code fields on the UB-04, see UB-04 revenue codes and condition codes, and for the full split, read our guide to facility vs professional billing. Our hospital and facility billing team handles both sides for facility clients.
- Medicare Claims Processing Manual, Chapter 26: Completing and Processing Form CMS-1500 Data Set · CMS
- Medicare Claims Processing Manual, Chapter 25: Completing and Processing the Form CMS-1450 Data Set · CMS
- Medicare Claims Processing Manual, Chapter 24: General EDI and EDI Support Requirements · CMS
- Medicare Claims Processing Manual, Chapter 1: General Billing Requirements · CMS
- Medicare Billing: CMS-1500 and 837P (MLN006976) · CMS MLN
- Medicare Billing: CMS-1450 and 837I (MLN006926) · CMS MLN
- Claim Adjustment Reason Codes · X12
We check every rule, code and deadline against the official source. See our editorial policy.
Common Questions
Straight answers from the team that does the work.
Ask a billing lead directly. A 20-minute call, Monday to Friday, 9am to 5pm Eastern.
01What is the difference between CMS-1500 and UB-04?
The CMS-1500 is the professional claim, used by physicians and other non-institutional providers, and the UB-04 is the institutional claim, used by hospitals and other facilities. The electronic versions are the 837P and 837I. They use different fields, so a claim on the wrong form is returned as invalid.
02Who bills on the CMS-1500 and who bills on the UB-04?
Physicians, nurse practitioners, physician assistants, therapists, clinical psychologists, chiropractors and ambulance services bill on the CMS-1500, according to MLN006976. Hospitals, critical access hospitals, skilled nursing facilities, home health agencies, hospices and ESRD facilities bill on the UB-04, according to MLN006926.
03What are 837P and 837I?
The 837P and 837I are the electronic versions of the professional and institutional claims. Medicare Claims Processing Manual Chapter 24 lists the current X12 versions as 005010X222A1 for professional claims and 005010X223A2 for institutional claims. The 837P matches the CMS-1500 and the 837I matches the UB-04.
04Does an ER bill both forms for one visit?
Usually yes. The hospital bills the facility visit and ancillary charges on the UB-04, and the emergency physician group bills its own services on the CMS-1500. They are separate claims with separate charges. Critical access hospitals using Method II are one exception, billing professional fees on the UB-04.
05Which form do freestanding ERs use?
There is no single Medicare rule in the claims manuals, so use the payer's own provider manual or contract. The facility fee is an institutional charge, and the physician fee is professional. A freestanding emergency department that bills both should confirm with each payer whether it wants one combined claim or two.
06Can a claim be rejected for using the wrong form?
Yes. Medicare returns submissions that do not conform to required claim formats as invalid, and says they are not considered claims. Other payers may reject or deny with CO-16 or CO-5. Correct the form and resubmit before the payer's filing deadline, because the first submission may not count.
Billing Both Sides of an ER Visit?
Our team prepares the facility claim and the professional claim as one workflow.