POS 23: Emergency Room - Hospital
POS 23 is the place of service code for a hospital emergency room: the portion of a hospital where emergency diagnosis and treatment of illness or injury is provided. It pairs with ED E/M codes 99281-99285, pays the Medicare facility rate, and is required for those codes to process cleanly.
- Setting
- Hospital emergency department
- Rate type
- Facility (lower professional payment)
- Common pairing
- ED E/M 99281-99285, critical care 99291
- Watch out for
- Patient admitted from the ER: admitting service bills POS 21
What does POS 23 mean?
POS 23 identifies the emergency room of a hospital: per CMS, a portion of a hospital where emergency diagnosis and treatment of illness or injury is provided. It is a facility POS code and the mandatory companion of the ED E/M family 99281-99285.
POS 23 belongs to the department, not the acuity. A patient who walks into the ED with a sore throat is still POS 23; a patient in extremis at an urgent care is still POS 20. The complete code table is in our Place of Service reference.
When do you use POS 23?
Use POS 23 for professional services rendered in the hospital emergency department:
- ED E/M 99281-99285 by emergency physicians and covering providers.
- Critical care 99291-99292 delivered in the ED.
- Consultants called to the ED who evaluate the patient there and discharge or refer (if the patient is admitted, subsequent services shift to POS 21).
- Procedures performed in the ED: laceration repair, reductions, chest tubes, with modifier 25 on the E/M when both are billed.
Hospital-affiliated freestanding EDs bill POS 23; independent freestanding emergency centers follow state and payer-specific rules and may not.
How does POS 23 affect payment?
POS 23 pays the professional claim at the Medicare facility rate. For emergency physicians this is the native economics of the specialty: the ED codes were valued with the facility setting assumed, and the hospital collects the facility fee that funds the department itself. There is no non-facility comparison to chase; ED codes effectively price at one rate.
The payment action at POS 23 is on the payer-behavior side: ED claims face downcoding programs (payers algorithmically reducing 99285 to 99283 based on final diagnosis), prudent layperson disputes, and No Surprises Act arbitration for out-of-network groups. Track your level distribution monthly; a sudden payer-specific shift toward lower levels on the ERA is a downcoding program, not a documentation change, and it is appealable. Benchmark expected payment per level with the Medicare fee calculator.
What are the common POS 23 errors and denials?
- CARC 5 mismatches: ED codes without POS 23, or office codes with it; check remits in the denial code lookup.
- Diagnosis-based downgrades and denials: plans denying or reducing ED claims because the final diagnosis looked minor. Appeal on prudent layperson grounds using presenting symptoms, not the discharge diagnosis.
- Split billing on admissions: both an ED code (POS 23) and initial hospital care (POS 21) billed by the same physician for the same date; the ED work folds into the admission code.
- Missing modifier 25 when an ED E/M accompanies a procedure, producing CO-97 bundling denials.
Frequently asked questions
As a rule, no. The ED E/M family is defined by the emergency department setting, and payers edit for POS 23 on those codes. A physician seeing a patient urgently in the office bills office E/M with POS 11, not an ED code. The one nuance is freestanding EDs: if hospital-affiliated and enrolled as part of the hospital, they still bill POS 23.
The ED physician who evaluated the patient in the department bills POS 23 for that encounter. The admitting physician's initial hospital care (99221-99223) carries POS 21, dated when the admission order was written. When one physician does both roles the services merge into the initial hospital care code with POS 21, per E/M rules on same-day services.
The professional claim itself prices at the facility rate, but the patient's big exposure is the hospital's ED facility fee and their plan's ER cost sharing tier. Note that emergency services carry special protections: the No Surprises Act limits balance billing by out-of-network ED physicians to in-network cost sharing, which directly affects what your group can pursue from the patient.
Because freestanding urgent care is POS 20, and ED codes with POS 20, or urgent care services miscoded as POS 23, trip CARC 5 edits. The reverse mistake, hospital-affiliated freestanding EDs billing POS 20 to look like urgent care, understates the setting and creates compliance exposure. Match the code to the enrollment status of the site.
Sources & further reading
Reviewed by the ImmediCare Solutions RCM team
Certified billers and coders handling claims across 50+ specialties nationwide. This entry is reviewed against current payer policy and CMS rules. Last review: Jul 5, 2026.
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