Does the No Surprises Act really change ER professional billing?

Substantially. Out-of-network emergency services must be billed at in-network cost sharing for the patient, and the remaining payment dispute goes through payer negotiation and IDR — not the patient's mailbox. POS 23 (and ER revenue codes) is how claims get identified for those protections.

A patient came to the ED and was admitted. Which POS for the ER physician?

POS 23 — the ER encounter happened in the ED, and the admission that followed doesn't retroactively relocate it. The admitting team's services after the inpatient order bill POS 21. Each professional claim reflects where and when its own service occurred.

POS 23 — Emergency Room — Hospital: Place of Service Code Explained

POS 23: What It Identifies

POS 23 identifies services in a hospital emergency department. ER professional billing carries its own E/M family, EMTALA context, and out-of-network rules (the No Surprises Act reshaped ER billing) — and POS 23 is the flag that turns those rules on.

The No Surprises Act, effective 2022, fundamentally changed what POS 23 means for patient billing: emergency services are now protected regardless of network status, meaning an out-of-network ER physician can no longer balance-bill the patient beyond in-network cost-sharing levels. Payment disputes between the payer and an out-of-network ER group now route through a federal independent dispute resolution process instead of the patient's wallet. POS 23 is the marker that triggers these protections — which makes accurate use of the code a compliance question, not just a payment one, since misclassifying an emergency encounter under a different POS could inadvertently strip away the patient protections the law requires.

Use POS 23 For

Emergency physician services in a hospital ED
Consultant services rendered IN the ED before disposition
Services in dedicated EDs, including freestanding EDs that qualify as hospital-based

Don't Use It For

Urgent care centers — POS 20, entirely different payment and network rules
Services after admission (POS 21 once inpatient status starts)
Hospital clinic visits that happen to be urgent — setting, not urgency, drives POS

How POS 23 Affects Payment

ER E/M codes (99281–99285) pair with POS 23, and payers scrutinize high-level ER codes constantly. The No Surprises Act caps patient cost sharing for out-of-network emergency care at in-network levels and routes payment disputes to arbitration — POS 23 claims are exactly where those protections apply, so balance-billing habits from the old world are now compliance violations.

Common POS 23 Billing Errors

Urgent care billed as POS 23 (or ER services as POS 20) — network and payment rules diverge sharply
Level-5 ER codes without documentation matching the intensity — the ED's chronic audit target
Consultants billing office POS for ED consults out of template habit

Documentation That Supports POS 23

ER E/M levels (99281-99285) live and die on documentation matching the actual complexity and risk of the encounter, and level-5 codes specifically draw ongoing payer review across the industry. The note needs to support the history, exam, and medical decision-making elements the billed level requires — not just describe what happened, but demonstrate the complexity that justified the resources and clinical judgment involved. For consultants seeing patients in the ED prior to a disposition decision, documenting that the encounter occurred in the ED (not a hospital room, not a clinic) supports the POS 23 designation on their own claim.

Real-World Scenario

A patient presents to a hospital ED with chest pain. A cardiologist is consulted and evaluates the patient in the ED before a decision is made to admit. The cardiologist's consult note should reflect the ED setting and the pre-admission timing — that consult bills POS 23. Once the admission order is written and the patient moves to an inpatient bed, any further cardiology follow-up bills POS 21 instead. A consulting group that defaults every ED consult to whatever POS their template last used, without checking the actual admission timeline, risks POS mismatches on exactly the claims most likely to face scrutiny given the higher-acuity nature of ED consults.

Related POS Codes

POS 21 — Inpatient POS 22 — On-campus outpatient POS 24 — ASC

← Back to the full POS code reference

Reviewed by Hassan Raza Awan, Founder — 4+ years of hands-on U.S. medical billing experience. General billing information — verify against current CMS guidance and your payer contracts.

POS 23: Emergency Room — Hospital