Revenue code 0451: EMTALA emergency medical screening
Revenue code 0451 is the UB-04 line for the medical screening examination that the Emergency Medical Treatment and Labor Act requires. It records the screening itself, apart from the emergency treatment that follows.
Written by Salman Saeed, CEO and Co-Founder · Reviewed by a Certified Medical Coder · Last reviewed October 2026In short: 0451 labels the EMTALA screening exam on a hospital outpatient claim. The duty to screen comes from 42 CFR 489.24 and applies whatever the patient's coverage. Neither Medicare chapter used here names 0451 separately, so the general 045x rules govern the claim.
What is revenue code 0451 used for?
The NCHS codebook labels 0451 as emergency room, EMTALA emergency medical screening services, effective October 1996. The next value, 0452, is labelled emergency room services beyond EMTALA screening, so the code set separates the screening from what happens afterward.
EMTALA is the federal law behind the screening duty, and 42 CFR 489.24 is the Medicare rule that carries it out. The revenue code is only a label on the UB-04. It does not show that the hospital met the law, and it does not set the visit level. NUBC wording is licensed, so this page paraphrases it.
What does the screening rule actually require?
Under 42 CFR 489.24(a)(1)(i), a hospital with an emergency department must give an appropriate medical screening examination to anyone who comes to the department, whether or not the person is eligible for Medicare and regardless of ability to pay. The exam must be within the capability of the department, including ancillary services routinely available to it, and its purpose is to determine whether an emergency medical condition exists.
The person doing the exam must be qualified under hospital bylaws or rules and meet the emergency services personnel requirements of 42 CFR 482.55. The rule does not say the screener must be a physician.
Screening is also not limited to the emergency department room. Section 489.24(b) says a person comes to the emergency department when they present on hospital property other than the dedicated emergency department and ask for examination or treatment for what may be an emergency medical condition. Whether a screening done in that setting is charged under 0451 is a policy question for your chargemaster and your payer. See EMTALA and billing.
How does 0451 sit on the claim?
Chapter 4 and Chapter 25 of the Medicare Claims Processing Manual do not mention 0451 by number. What they say about the 045x family is what governs the line:
- Section 180.6 of Chapter 4: emergency room services from hospital outpatient departments are reported under the 045x revenue codes.
- Section 20.1 of Chapter 4: acute care hospitals report HCPCS codes for the services rendered.
- Chapter 25, FL 70A to 70C: reason for visit is required on type of bill 013x and 085x when a 045x code is present and the FL 14 priority of visit is code 1, 2 or 5.
- Section 240.1 of Chapter 4: 045x is on the list of revenue codes Medicare edits against on type of bill 012x.
Which visit code sits beside 0451 is not set by those chapters. Type A emergency departments use CPT 99281 to 99285 and Type B departments use G0380 to G0384, according to section 160. A payer may publish its own list of codes it accepts with 0451, so pull the current list from the payer manual instead of assuming one.
Which emergency departments count as dedicated?
The EMTALA rule applies to a hospital's dedicated emergency department. Chapter 4 section 160 repeats the 42 CFR 489.24 test: a department qualifies if it is licensed by the state as an emergency room or department, if it is held out to the public as a place that treats emergency medical conditions on an urgent basis without an appointment, or if at least one-third of its outpatient visits in the prior calendar year were for such conditions.
A hospital-run walk-in clinic can therefore be a dedicated emergency department even if the building calls itself something else. If that is your site, review the choice between 0450 and 0456 together with your compliance officer.
Where does revenue code 0451 sit on the claim, and what does the remittance show?
The EMTALA screening line carries 0451 in FL 42. FL 44 still needs the HCPCS code for the visit. The three-part dedicated ED test decides whether the department qualifies at all.
When the payer rejects the line, read the group code first. CO with CARC 16 means a billing error to correct. A PR group with CARC 96 and RARC M28 is the CMS pattern for a non-allowed revenue code on a 12x bill.
A screening-only visit bills 0451 with a visit code and no other lines.
Why do 0451 lines get denied?
| Code | What X12 says | Where it shows up on a 0451 line |
|---|---|---|
| CO-16 with RARC M51 | Claim lacks information or has a billing error; M51 is missing, incomplete or invalid procedure code | Screening line billed with no HCPCS code, or reason for visit missing on the claim |
| CO-50 | Non-covered because the payer does not deem it medically necessary | A screening-only visit the payer reviews as not an emergency |
| CO-97 | The benefit is included in the payment for another service already adjudicated | The screening folded into the visit payment, so a separate 0451 line pays nothing |
If these denials keep coming back, our denial management team can work them. Sibling lines are 0459 and the professional fee code 0981.
Related codes
- Restricted-use Linked NCHS-CMS Medicare Data: Outpatient Revenue Center codebook · CDC / NCHS
- 42 CFR 489.24, Special responsibilities of Medicare hospitals in emergency cases · eCFR
- Medicare Claims Processing Manual, Chapter 4: Part B Hospital (Including Inpatient Hospital Part B and OPPS) · CMS
- Medicare Claims Processing Manual, Chapter 25: Completing and Processing the Form CMS-1450 Data Set · CMS
- Claim Adjustment Reason Codes · X12
- Remittance Advice Remark Codes · X12
- Medicare Claims Processing Manual, chapter 25, section 75 (UB-04 form locators 42 and 44) · CMS
- Medicare Claims Processing Manual, chapter 22, sections 60.1 to 60.3 (group codes, CARC, RARC on the remittance) · CMS
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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 revenue code 0451 used for with EMTALA screening?
It labels the medical screening examination EMTALA requires, on the hospital's UB-04 outpatient claim. The NCHS codebook describes it as emergency room, EMTALA emergency medical screening services. It is a charge category only and does not replace the visit code or prove EMTALA compliance.
02Does the EMTALA screening depend on insurance?
No. 42 CFR 489.24(a)(1) requires the screening exam whether or not the person is eligible for Medicare and regardless of ability to pay. Coverage affects how the hospital bills afterward and who pays, but it does not change whether the hospital must screen the patient.
03Does a screening exam have to be done by a physician?
The regulation does not say so. Section 489.24(a)(1)(i) requires an individual determined qualified by hospital bylaws or rules who also meets the emergency services personnel requirements of 42 CFR 482.55. Your bylaws decide who qualifies, and the chart should show who did the exam.
04Is 0451 billed with 0450 on the same claim?
The codebook lists them as separate values, so a claim can carry both when the hospital charges the screening apart from other emergency care. Chapter 4 does not require or forbid the pair. Follow the payer's published instructions and your own chargemaster.
05What happens when the patient is admitted after screening?
Under 489.24(a)(1)(ii) and (d)(2), if the hospital admits the person as an inpatient for further treatment, its EMTALA obligation to stabilize ends. How the earlier emergency charges are reported then depends on the hospital inpatient billing rules, which this page does not cover.
Screening charges getting packaged or denied?
We check how each ER line is labelled against the payer's own rules before the claim goes out.