POS code 55: Residential Substance Abuse Treatment Facility.

The CMS definition

A facility which provides treatment for substance (alcohol and drug) abuse to live-in residents who do not require acute medical care. Services include individual and group therapy and counseling, family counseling, laboratory tests, drugs and supplies, psychological testing, and room and board.

That is the description CMS publishes for POS 55, Residential Substance Abuse Treatment Facility, in the Place of Service Code Set and in chapter 26 of the Medicare Claims Processing Manual. In the manual’s table it carries the Non-facility rate (NF) designation for payment under the Physician Fee Schedule.

What it means in plain terms

POS 55 is for live-in treatment. The patient lives at the facility, which is what separates it from POS 57 (non-residential), where treatment is on an ambulatory basis. CMS lists the services as individual and group therapy and counseling, family counseling, laboratory tests, drugs and supplies, psychological testing, and room and board.

When it is used

• A service is furnished at a facility where residents live in and receive substance abuse treatment without needing acute medical care.
• If the patient is treated on an ambulatory basis and does not live at the facility, the CMS list points to POS 57 (non-residential substance abuse treatment) or POS 58 for opioid treatment.

Billing implications (Medicare)

The manual marks POS 55 NF, so Medicare physician fee schedule services are paid at the non-facility rate.

CMS gives POS 58 (non-residential opioid treatment facility) its own note: opioid use disorder treatment at Opioid Treatment Programs is not considered a physician service and is separately paid under a bundled payment. That note applies to 58, not 55.

The general rule in section 10.6 of the manual is that the POS code “generally” reflects the actual setting where the beneficiary receives the face-to-face service, with two exceptions: a registered hospital inpatient or outpatient is reported with the hospital code regardless of where the encounter happens. The code goes in item 24B of the paper Form CMS-1500 or the matching field of the 837P.

Look-alike codes

• POS 57: Non-residential substance abuse treatment facility. Ambulatory treatment.
• POS 56: Psychiatric residential treatment center. Facility rate.
• POS 58: Non-residential opioid treatment facility.
• POS 53: Community mental health center. Facility rate.

For every code in one list, with the 02 vs 10 vs 11 telehealth verdict, see the place of service code lookup.

Sources

• CMS: Place of Service Code Set — official code list and descriptions, page database updated May 2, 2024 (retrieved 2026-11-02)
• CMS: Medicare Claims Processing Manual, Chapter 26 (Rev. 12779, issued 08-09-24) — sections 10.5 and 10.6, facility and non-facility designations and special considerations (retrieved 2026-11-02)

Every definition and rule above was read from these CMS pages on November 2, 2026. Payers revise code lists, contracts and policies, so confirm anything that affects a claim with the payer. CMS itself tells billers to check each payer (Medicare, Medicaid, private plans) for how it reimburses each code.