Place of Service Codes That Change Payment

The place of service code is two digits in box 24B of the CMS-1500. It tells the payer where the patient received the service, and it selects which practice expense rate the claim is priced against. Get it wrong in the direction of the higher rate and the difference becomes a recoverable overpayment. Get it wrong the other way and the practice is paid less than the work earned.

The POS code is a price signal before it is a data field. It tells the payer which overhead the practice carried, and the claim is paid accordingly.The allowed amount follows the setting, not the complexity of the visit.

The medical coding side of this is simple to state and easy to get wrong: one two-digit code decides which of two Medicare rates applies to a service. This article covers what the POS code does to the allowed amount, the codes that drive most outpatient claims, the settings where the obvious answer is wrong, and the checks that keep a wrong code off the claim.

The two-digit field that sets the price

A place of service code is two digits. CMS maintains the set, and the HIPAA Transaction and Code Set Rule makes it the code set for the site of service on professional claims. On a paper CMS-1500 the code sits in box 24B. On the 837P electronic claim it sits in loop 2400, segment SV105. The field is per line, so a claim with services in two settings needs two POS values.

The code does more than name a room. Under the Medicare Physician Fee Schedule, most codes carry two payment amounts: a facility rate and a non-facility rate. The POS code on the claim decides which one the payer applies. That single field is the difference between the office rate and the hospital rate for the same CPT code, the same patient, and the same day.

The two rates exist because Medicare does not want to pay twice for the same overhead. When a hospital or facility already bills for the room, the staff, and the supplies, the practitioner’s claim is priced at the facility rate. When the practice carries that overhead itself, the non-facility rate applies. Work RVUs and malpractice RVUs do not change with the setting. Only the practice expense RVU does.

The medical coding and billing workflow usually sets the POS code from a software default or the provider’s billing address. Neither is the rule. The rule is the setting where the patient received the face-to-face service, with two exceptions covered below.

Facility and non-facility: the money behind the code

The difference between the two rates lives in the practice expense (PE) component. A facility rate strips out the PE dollars the facility recovers on its own claim. A non-facility rate keeps them, because the practice paid for the exam room, the front desk, and the supplies.

The rule for hospital patients is not about the room where the visit happened. For a service furnished to a hospital inpatient (POS 21) or a hospital outpatient (POS 19 or 22), Medicare pays the facility rate no matter where the face-to-face encounter occurred. A physician who sees a registered inpatient in a conference room across the street still bills POS 21. For the professional component of a diagnostic test, the facility and non-facility rates are the same, so the POS code does not move the money there.

The gap widened for 2026. CMS finalized a change to the indirect practice expense methodology so that facility settings no longer receive the same indirect cost allocation as office settings. The AMA analysis of the final rule puts the effect at a 7 percent decrease for physician services furnished in facility settings and a 4 percent increase for the same services furnished in non-facility settings. The 2026 conversion factors are $33.57 for qualifying APM participants and $33.40 for everyone else.

The codes that matter most in outpatient billing

A handful of codes cover most outpatient claims. Learn the rate each one triggers and the pairs that get mixed up.

Three pairs cause most of the trouble. First, 11 against 22 or 19: a private office pays the non-facility rate, and a hospital outpatient department pays the facility rate, even when the two look alike. Second, 02 against 10: Medicare accepts only those two codes for telehealth, and 02 pays the facility rate while 10 pays the non-facility rate. Third, 31 against 32: a skilled nursing facility stay covered by Part A pays the facility rate, and a nursing facility or a SNF stay past Part A pays the non-facility rate.

One more pair belongs here. An ambulatory surgical center (POS 24) is a facility setting even when the surgeon owns it, and a provider-based clinic on a hospital campus is POS 22 even when it runs like a private office. The lease and the provider-based designation decide the code, not the paint on the wall.

Sites where the right answer is not obvious

Telehealth. For Medicare, the POS code reflects where the patient is, not where the clinician is. POS 10 applies when the patient is in their home, and POS 02 applies when the patient is somewhere else. Pair the code with modifier 93 for audio-only or modifier 95 for audio and video. The modifier does not change the payment rate; the POS code does. Commercial payers set their own rules, and several still ask for the office code with modifier 95, so read the payer policy before you default. See telehealth billing rules for the modifier detail.

Home and residence visits. Since January 1, 2023, the home or residence E/M family (99341 through 99350) covers a private home, an assisted living facility, a group home, a custodial care facility, and a residential substance abuse treatment facility. The POS code follows the setting: 12 for a home, 13 for assisted living, 14 for a group home, 33 for custodial care, and 55 for residential substance abuse treatment. The old domiciliary codes 99324 through 99337 are deleted.

Mobile units. A mobile unit has its own code (15), and Medicare pays it at the non-facility rate. The special rule is that when the unit travels to an entity that already has a POS code, such as a physician office or a skilled nursing facility, the claim uses that entity’s code rather than 15. Use 15 only when the unit is not serving a place that a code already describes.

Behavioral health in schools. A school is POS 03, and Medicare pays services there at the non-facility rate. School-based Medicaid billing runs on state rules rather than one national policy. A state may ask for POS 03 for a service delivered in a school building and a different code for a home visit under the same program. When a student is seen by telehealth from a school, the POS code reflects where the student sits. Check school-based services billing guides before you assume 03, and apply the same care to ABA therapy billing in a clinic or a home.

Residential and outpatient behavioral health settings. The facility and non-facility split does not follow how intensive the care feels. A psychiatric residential treatment center (56) is a facility setting, while a residential substance abuse treatment facility (55) is non-facility.

Nursing facility visits. Use 31 during a covered Part A SNF stay and 32 for a nursing facility or a SNF stay after Part A benefits run out. MM13767, the CMS education article on this, says the system rejects a professional claim with POS 32 that overlaps a processed Part A SNF claim, and adjusts a paid POS 32 claim when a SNF claim for the same stay arrives later. That is an automated recovery, not a letter you can argue with.

What a wrong code costs

The cost runs in both directions. Bill the office rate (11) for a hospital outpatient service and Medicare pays more than the service earned. That difference is a recoverable overpayment. Recovery Audit Contractor topic 0108, Facility versus Non-Facility Reimbursement: Incorrect Coding, covers exactly this, and it applies across every A/B MAC jurisdiction.

The OIG measured the size of the SNF and nursing facility version of the problem. In an audit of 2019 and 2020 claims, Medicare paid $22,463,193 too much on 1,130,182 claim lines by applying the non-facility rate to services coded as furnished in a nursing facility or a SNF without Part A coverage while the patient was a Part A SNF inpatient. A second group, services coded as non-facility while the patient was a Part A SNF or hospital inpatient, added $22,142,489 on 1,012,203 lines.

The other direction is quieter. Bill the facility rate for work done in the office and the practice is paid less than the non-facility rate the claim earned. No payer flags an underpayment, so the loss repeats every week until someone reconciles the allowed amount against the fee schedule.

When the code is wrong, the fix is a corrected claim, not an appeal. The replacement claim carries the correct POS code and is tied to the original claim number, and the payer reprocesses the whole claim.

How to keep the POS right on every claim

The POS code is set by the encounter, so the check belongs at the encounter. Route it through the same steps every time.

• The POS code matches the setting recorded on the encounter form.
• Telehealth lines use 02 or 10 based on where the patient sat, not where the clinician sat.
• Registered hospital inpatients and outpatients carry 21, 19, or 22 even if seen elsewhere.
• Part A SNF stays use 31, and everything else in a nursing facility uses 32.
• Home or residence visits carry 12, 13, 14, 33, or 55 to match the setting.
• The paid amount matches the facility or non-facility column the POS code selected.
• A correction is filed as a corrected claim, not an appeal.

A chart audit that reads the same encounter forms your coders read is the fastest way to find a POS pattern before a contractor does. comprehensive chart auditing is where that check lives.

Place of service code questions

This article is general information about Medicare place of service coding, not legal advice, and the current CMS code set and your payer’s policy control.