Hyperbaric Oxygen Therapy CPT Codes: Billing Guide for Providers & Patients

The primary CPT code for hyperbaric oxygen therapy is 99183, which covers physician attendance and supervision of an HBOT session. The facility code is HCPCS G0277, billed in 30-minute segments. Together, these two codes account for nearly all HBOT billing in outpatient and clinic settings. For CY 2025, Medicare pays facilities $137.90 per 30-minute G0277 segment, and physician payment for 99183 averaged roughly $109 per session in recent Medicare claims data.^[2][3]

Three codes in three sentences: CPT 99183 is the physician’s supervision fee, billed once per session. HCPCS G0277 is the facility’s chamber fee, billed per 30-minute interval. C1300 is a retired code that G0277 replaced on January 1, 2015, and it no longer belongs on any claim.^[5]

What Is CPT Code 99183?

CPT code 99183 is defined as “physician or other qualified health care professional attendance and supervision of hyperbaric oxygen therapy, per session.” It is the professional-component code representing the clinical oversight provided during each treatment session.

What 99183 Covers

This code covers the physician’s active, in-person supervision during the session, including monitoring the patient’s physiological response, adjusting treatment parameters as needed, and managing any complications that arise under pressure. It does not cover facility costs, oxygen, or technical staff. Understanding how these codes reimburse helps explain the wider picture of hyperbaric chamber cost, which combines physician fees, facility charges, and session counts.

Medicare Reimbursement for 99183

The exact allowed amount varies by geographic locality and payment year; the authoritative number for any date of service comes from the CMS Physician Fee Schedule Look-Up Tool.^[4] As a benchmark, Medicare claims data analyzed by Gelly and colleagues (2024, Undersea & Hyperbaric Medicine) put average physician payment at $4,346.40 per 40-treatment course in 2022, about $109 per session.^[3] The CY 2026 Physician Fee Schedule final rule raised the conversion factor about 3.26% to $33.40, which lifts 99183 payments modestly for 2026 dates of service.^[4]

What Is HCPCS G0277 and How Is It Billed?

G0277 covers “hyperbaric oxygen under pressure, full body chamber, per 30-minute interval.” This is the facility-side code accounting for the chamber, technical staff, monitoring equipment, and overhead. Treatment time runs from start of pressurization to end of depressurization. A typical 90-minute session is billed as 3 units of G0277 ($413.70 at CY 2025 Medicare rates).^[2]

What Happened to Code C1300?

C1300 carried the identical descriptor (“hyperbaric oxygen under pressure, full body chamber, per 30 minute interval”) but was discontinued December 31, 2014. CMS replaced it with G0277 effective January 1, 2015, and unlike C1300, G0277 is not limited to hospital outpatient sites of service.^[5] Claims submitted with C1300 for dates of service after that switch reject at the payer level. If you see C1300 referenced in current billing guidance, the guidance is out of date.

Which ICD-10 Codes Pair with HBOT Claims?

Every HBOT claim must include a diagnosis code matching one of the 15 Medicare-covered indications in National Coverage Determination 20.29. Without a matching ICD-10 code, the claim will be denied.^[1] The table below lists example codes for all 15 covered conditions; your Medicare Administrative Contractor’s billing article controls the exact accepted code list.

*For diabetic wounds, Medicare requires both a diabetes ICD-10 code and a wound site code. The wound must be Wagner grade III or higher and must have failed an adequate course of standard wound therapy, defined as no measurable signs of healing for at least 30 consecutive days.^[1]

What Documentation Does Medicare Require for HBOT?

Insufficient documentation is the leading cause of HBOT claim denials. Every treatment note must include:

• A statement confirming the physician was physically present and actively supervising the session
• Treatment pressure in atmospheres absolute (ATA)
• Oxygen concentration delivered
• Total session duration (start of pressurization to end of depressurization)
• Patient clinical response and any adverse events
• Clinical rationale linking treatment to a covered diagnosis

For diabetic wound indications, the record must also show re-evaluation at least every 30 days during treatment: continued HBOT is not covered if measurable signs of healing have not been demonstrated within any 30-day treatment period.^[1]

Do You Need Prior Authorization for HBOT?

Traditional Medicare does not currently require prior authorization for HBOT. CMS ran a prior authorization model for non-emergent HBOT in Illinois, Michigan, and New Jersey from 2015 through 2018, but that demonstration ended.^[6] HBOT is also not on the service list for CMS’s WISeR prior-authorization model that began January 1, 2026 in six states.^[7]

Commercial insurers and many Medicare Advantage plans are a different story: most require prior authorization before non-emergency HBOT begins. Starting treatment before authorization is secured places the provider at financial risk for the entire course. For wound-related indications, document at least 30 days of standard wound care without adequate improvement before requesting authorization, and confirm Wagner grade III or higher for diabetic wounds.

How Much Does Medicare Reimburse for HBOT Overall?

The G0277 facility rate increased from $132.21 (CY 2024) to $137.90 (CY 2025).^[2] The longer trend runs the other way for physicians: Gelly et al. (2024) found physician payment per 40-treatment course fell 37.8% from 2013 to 2022 ($5,993.16 to $4,346.40), while the total Medicare cost per 40-session course fell 15.6% over the same period, from $27,561.74 to $23,834.40.^[3] For how these reimbursement figures compare with the therapy’s value case, see our HBOT cost-effectiveness data.

For Patients: How Do You Read an HBOT Bill?

A typical HBOT bill includes two main charges per session. The physician supervision fee (CPT 99183) covers the doctor who monitored your treatment. The facility or chamber fee (G0277) covers the time you spent in the chamber, billed in 30-minute increments. Additional services such as wound debridement appear as separate line items.

Before your first session: ask for the exact CPT and ICD-10 codes your provider plans to submit, confirm coverage and session limits with your insurer, and request prior authorization confirmation in writing. For full coverage details, see our HBOT insurance coverage guide, and for how self-pay session prices vary regionally, our HBOT cost by state breakdown.

Seph Fontane Pennock

Author

Seph Fontane Pennock is the founder of BaricBoost.com and Regenerated.com, a clinic directory for regenerative medicine serving 10,000+ providers across the United States. He previously built and sold PositivePsychology.com, which grew to 19 million users and became the largest evidence-based positive psychology resource on the web. Seph brings direct experience as an HBOT patient, having completed protocols at clinics across three continents while navigating mold illness, systemic inflammation, and autoimmune conditions. His treatment journey includes hyperbaric oxygen therapy, peptide protocols, NAD+ therapy, and consultations with specialists from Dubai to Cape Town to Mexico. This combination of entrepreneurial track record and lived patient experience shapes everything published on BaricBoost.com. Every article is grounded in peer-reviewed research, informed by real clinical encounters, and written for patients making high-stakes treatment decisions. Seph's focus is on bringing transparency, scientific rigor, and practical guidance to the hyperbaric oxygen therapy space.

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