HCPCS G0277: hyperbaric oxygen therapy, per 30 minutes
G0277 reports hyperbaric oxygen under pressure in a full-body chamber, counted per 30-minute interval, so a 90-minute session is 3 units. Medicare pays it only for the conditions on the covered list in National Coverage Determination 20.29, and a diagnosis outside that list denies as not medically necessary.
Written by Salman Saeed, CEO and Co-Founder · Reviewed by a Certified Medical Coder · Last reviewed October 2026In short: G0277 is billed once per 30-minute interval, with an NCCI MUE of 5 per date of service, and Medicare allows it only in a hospital outpatient department. NCD 20.29 limits coverage to 15 listed conditions, and the physician's attendance and supervision is billed separately with 99183.
What does G0277 report, and how are units counted?
G0277 is the HCPCS descriptor "Hyperbaric oxygen under pressure, full body chamber, per 30 minute interval". One unit is one 30-minute interval of chamber time, taken from the chamber log, so the claim units follow the recorded session length.
In the October 2026 fee schedule file (RVU26D) it has status A, an XXX global and a work RVU of 0.00. Its PC/TC indicator is 3, which the file layout defines as a technical-component-only code, so the payment is practice expense, not physician work. The NCCI MUE is 5 per date of service with indicator 3, a clinical edit, in both the practitioner and outpatient hospital tables, which caps a day at 150 minutes.
| Point | G0277 | 99183 |
|---|---|---|
| What it reports | Chamber treatment, per 30 minutes | Physician attendance and supervision, per session |
| Work RVU (RVU26D) | 0.00 | 2.06 |
| PC/TC indicator | 3, technical only | 2, professional only |
| MUE (Q4 2026) | 5 | 1 |
| Who bills it | The hospital outpatient department | The supervising physician |
Which conditions does NCD 20.29 cover?
Section 20.29 of the National Coverage Determinations Manual limits coverage to treatment given in a chamber, including a one-person unit, for 15 conditions. Each is a diagnosis the claim must carry, and the diagnosis is what the MAC checks first.
| # | Covered condition | Condition in the NCD |
|---|---|---|
| 1 | Acute carbon monoxide intoxication | |
| 2 | Decompression illness | |
| 3 | Gas embolism | |
| 4 | Gas gangrene | |
| 5 | Acute traumatic peripheral ischemia | Adjunct, when loss of function, limb or life is threatened |
| 6 | Crush injuries and suturing of severed limbs | Adjunct, same threat standard |
| 7 | Progressive necrotizing infections (necrotizing fasciitis) | |
| 8 | Acute peripheral arterial insufficiency | |
| 9 | Compromised skin grafts | Preparation and preservation, not primary wound management |
| 10 | Chronic refractory osteomyelitis | Unresponsive to conventional medical and surgical management |
| 11 | Osteoradionecrosis | Adjunct to conventional treatment |
| 12 | Soft tissue radionecrosis | Adjunct to conventional treatment |
| 13 | Cyanide poisoning | |
| 14 | Actinomycosis | Adjunct, when refractory to antibiotics and surgery |
| 15 | Diabetic wounds of the lower extremities | Three criteria, with reevaluation every 30 days |
Everything not on the list is not covered. Section B names cutaneous, decubitus and stasis ulcers, chronic peripheral vascular insufficiency and thermal skin burns among the conditions Medicare will not pay for. The diabetic criteria and the notes that prove them are on wound care billing.
How does G0277 go on the claim?
Claims Processing Manual chapter 32, section 30.1, sends hospital claims on the 837 institutional format, or rarely on the CMS-1450, with bill types 11X, 13X and 85X. It says G0277 is not available outside a hospital outpatient department, and that a skilled nursing facility folds HBO into the Part A stay payment.
| Setting | How it is reported |
|---|---|
| Hospital outpatient | G0277 per 30-minute interval, with 99183 for the physician |
| Inpatient, and critical access hospital not electing Method I | Revenue code 940 with no HCPCS code; ICD-10-PCS 5A05121 on inpatient claims |
| Critical access hospital, Method I | Revenue code 940 with HCPCS 99183 |
| Physician or practitioner | 837P or CMS-1500 with 99183 and G0277; paid from the fee schedule, deductible and coinsurance apply |
The manual says claims with invalid diagnosis codes are denied as not medically necessary. Hospital payment runs through the APC or the inpatient DRG, and the denial notice uses MSN 16.48 or 15.4. NCCI Chapter XI adds that 99183 already includes the E/M work tied to the session, such as the pressure and complication checks, so no E/M is billed for it. An unrelated, significant and separately identifiable visit the same day takes modifier 25.
Is topical oxygen billed with G0277?
No. Chapter 32 says topical application of oxygen does not meet the definition of HBO therapy, because HBO exposes the entire body to oxygen under increased pressure, and that no Medicare payment is made for it under section 30.1. Since April 3, 2017 the NCD leaves topical oxygen for chronic wounds to each MAC. A wound center that also debrides, for example with 97597, bills those services on their own lines.
Which fields carry hyperbaric oxygen sessions?
A hospital outpatient department lists each session date as a line. FL 42 holds the revenue code, FL 44 holds G0277, FL 45 holds the date and FL 46 holds the number of 30-minute intervals.
RVU26D gives G0277 status A, and the MUE table allows 5 per date with indicator 3.
Example: A patient with a diabetic foot wound receives a 90 minute session on 10/12, so 3 intervals. The line is G0277, 3 units, diagnosis in FL 67, $620.00. A claim for 6 intervals on one date goes over the MUE of 5.
Why is G0277 denied?
| CARC | What X12 says | What usually causes it |
|---|---|---|
| 50 | Non-covered because the payer does not deem it medically necessary | No documented failure of standard wound therapy, or no 30-day wound reevaluation |
| 167 | The diagnosis is not covered | A diagnosis not on the NCD 20.29 list, such as a stasis ulcer |
| 11 | The diagnosis is inconsistent with the procedure | Wound code listed first, with no diabetes diagnosis on the claim |
| 151 | The information submitted does not support this many or this frequency of services | More than 5 units on a date of service |
| 96 | Non-covered charge | Topical oxygen billed as HBO |
If these denials keep coming back, our denial management team can work them.
Related codes
- Physician Fee Schedule relative value files, RVU26D (October 2026) · CMS
- Medicare NCCI Medically Unlikely Edits, practitioner and outpatient hospital tables, effective 10-01-2026 · CMS
- 2026 NCCI Medicare Policy Manual, Chapter XI: Medicine and Evaluation and Management Services · CMS
- Medicare National Coverage Determinations Manual, Chapter 1, Part 1 (section 20.29, Hyperbaric Oxygen Therapy) · CMS
- Medicare Claims Processing Manual, Chapter 32: Billing Requirements for Special Services · CMS
- HCPCS quarterly update, October 2026 alpha-numeric file · CMS
- Claim Adjustment Reason Codes · X12
- Medicare Claims Processing Manual, Chapter 26: Completing and Processing Form CMS-1500 Data Set · CMS
- Medicare Claims Processing Manual, Chapter 25: Completing and Processing the Form CMS-1450 Data Set · CMS
We check every rule, code and deadline against the official source. See our editorial policy.
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 are the coverage criteria for hyperbaric oxygen (G0277)?
NCD 20.29 covers hyperbaric oxygen in a chamber for 15 listed conditions, from carbon monoxide intoxication and gas gangrene to diabetic wounds of the lower extremities. Diabetic wounds also need Wagner grade III or higher and no healing after 30 days of standard care. Other indications are not covered.
02How many units of G0277 can I bill?
One unit per 30-minute interval. The NCCI MUE for G0277 effective October 1, 2026 is 5 per date of service, so a day is capped at 150 minutes of chamber time. The same MUE appears in the practitioner and the outpatient hospital tables.
03Can a physician office bill G0277?
Chapter 32 says G0277 is not available for use other than in a hospital outpatient department. The practitioner section of the same chapter lists it, with 99183, for physician claims, paid from the fee schedule. Facility rules and place of service decide who bills which code.
04What is billed with G0277?
The supervising physician bills 99183 once per session. NCCI Chapter XI says 99183 includes the related E/M work, so no E/M is billed for it, but an unrelated, significant and separately identifiable E/M the same day can carry modifier 25.
05Does Medicare pay for topical oxygen on a wound?
Not as hyperbaric oxygen. Chapter 32 says topical application of oxygen does not meet the HBO definition and no payment is made for it under that section. Since April 3, 2017 the NCD leaves coverage of topical oxygen for chronic wounds to each MAC.
Hyperbaric claims denied for medical necessity?
We check the diagnosis against NCD 20.29 and the chamber log against the units before billing.