Open treatment of a palatal or maxillary fracture requiring complex repair, including internal fixation or other stabilization techniques.

Verified May 8, 2026 · 4 sources ↓

Medicare: $721.79
Work RVU: 10.58
Global, days: 90
Region: Other

Drawn from CMSHHS

Documentation requirements

What must appear in the operative or office note to support the claim.

Source · Editorial brief grounded in 4 cited references ↓

Operative note must name the specific fracture pattern (palatal, maxillary, or combined) and the number of fragments addressed
Fixation method must be documented explicitly — e.g., plate and screw internal fixation, external fixation, or wire fixation with complexity factors
Distinguish complexity elements that separate 21423 from 21422, such as comminution, displacement degree, or requirement for bone grafting
Imaging (CT of facial bones) confirming fracture pattern and displacement must be referenced in the operative or admission note
Document any concurrent craniofacial or zygomatic involvement separately to support or exclude add-on or companion codes
For inpatient billing: admission status and medical necessity for inpatient level of care must be documented per Two-Midnight Rule requirements

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 51 Multiple procedures 52 Reduced services 57 Decision for surgery 58 Staged or related 62 Co-surgeons 74 Discontinued post-anesthesia 78 Unplanned return — related 79 Unrelated during global 80 Assistant surgeon AS PA/NP/CNS assistant LT Left side RT Right side

What this code covers

Source · Editorial summary grounded in 4 cited references ↓

CPT 21423 covers open surgical treatment of a palatal or maxillary fracture at its most complex level — distinguished from 21422 (open treatment without complexity) and 21421 (closed treatment with interdental wire fixation) by the involvement of internal fixation hardware, multiple fragment reduction, or other complexity factors requiring operative exposure. This is a 90-day global procedure with a high work intensity, reflecting the anatomic difficulty of palatal and maxillary fracture repair.

This code is listed as an inpatient-only procedure under CMS Addendum E, meaning Medicare will not pay for it when performed in a hospital outpatient department or ASC under standard OPPS rules — it must be billed as an inpatient admission. Coders billing for commercial payers or Medicaid should verify site-of-service coverage separately, as those programs are not bound by OPPS inpatient-only status. Trauma surgeons and oral-maxillofacial surgeons are the primary billers; orthopedic surgeons may co-manage or assist in polytrauma cases.

Documentation must distinguish this from 21422 by explicitly identifying the complexity elements — number of fragments, fixation method, and any concurrent craniofacial involvement. If concurrent craniofacial separation repair (e.g., 21431–21436) is performed, carefully review NCCI edits before reporting both. The 90-day global encompasses all routine post-op management; unrelated conditions treated during that window require modifier 24 on the E/M or modifier 79 on a separate surgical procedure.

RVU & reimbursement

Component RVUs and Medicare national rate. Actual payment varies by GPCI locality.

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU vs. total RVU

The work RVU (10.58) is the surgeon's own effort — the figure physician pay and productivity targets are built on. The total RVU (21.61) adds practice overhead and malpractice, and is what drives the Medicare payment below.

Work RVU	10.58
Practice expense RVU	9.07
Malpractice RVU	1.96
Total RVU	21.61
Medicare national rate	$721.79
Global period	90 days

Payment by site of service

Medicare pays different rates by setting. HOPD typically pays substantially more than ASC for the same procedure.

Source · CMS OPPS Addendum B·ASC HCPCS payment rates·2026

Setting	Medicare rate (national)
Office (PFS non-facility) Procedure performed in physician's office	$721.79
HOPD (APC 5165) Hospital outpatient department	$6,048.05
ASC (PI J8) Ambulatory surgical center (freestanding)	$4,839.69

Common denial reasons

The recurring reasons claims for CPT 21423 get rejected.

Source · Editorial brief grounded in CMS NCCI edits, AAOS coding appeals, and cited references ↓

Billed in an outpatient or ASC setting — 21423 is inpatient-only under Medicare OPPS and will be denied with status indicator C
Operative note fails to document complexity distinguishing 21423 from the lower-complexity 21422, triggering downcoding
Missing or inadequate imaging documentation to support open treatment medical necessity
Global period violations: separate E/M or minor procedures billed within the 90-day global without appropriate modifier 24 or 79
Concurrent craniofacial codes billed without verifying NCCI bundling edits, resulting in one code being denied as inclusive

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 4 cited references ↓

01Why is 21423 inpatient-only under Medicare?

CMS assigned 21423 status indicator C under OPPS Addendum E, meaning the agency determined the procedure is too resource-intensive or clinically complex to be performed safely in a hospital outpatient or ASC setting. Medicare will not reimburse the facility for this code outside an inpatient admission. Physician billing (Part B) follows separately.

02What separates 21423 from 21422?

Both involve open treatment of a palatal or maxillary fracture. 21423 is the complex variant — typically involving internal fixation hardware, comminuted fragments requiring individual reduction, or other technical complexity. 21422 is open treatment without that complexity tier. Your operative note must make the distinction explicit; payers audit this pair frequently.

03Can 21423 be billed with concurrent craniofacial separation codes?

Possibly, but check NCCI edits first. Codes in the 21431–21436 range address craniofacial separation and may be bundled with 21423 depending on the edit. If the craniofacial and palatal/maxillary repairs are anatomically distinct and separately documented, modifier 59 or XS may apply — but confirm the edit type before appending a modifier.

04How does the 90-day global period affect billing for post-op complications?

All routine post-op care is included through day 90. If you return the patient to the OR for a related complication, use modifier 78. For an unrelated surgical procedure during the global, use modifier 79. An unrelated E/M visit in the global requires modifier 24 with documentation that the visit addressed a problem unconnected to the fracture repair.

05Does the inpatient-only designation affect commercial payer billing?

No — the inpatient-only list is a Medicare OPPS construct. Commercial payers and Medicaid programs set their own site-of-service rules. Some follow CMS policy, others don't. Verify with each payer's fee schedule or coverage policy before assuming the inpatient-only restriction applies outside Medicare.

06Should modifier 22 ever be used with 21423?

Yes, when the complexity substantially exceeds what the code typically describes — for example, severe comminution requiring extensive reconstruction or significant additional operative time. Documentation must quantify the additional work: operative time, number of fragments, or intraoperative challenges. Without that, payers will disallow the increased complexity claim.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

01CMS Physician Fee Schedule 2026
02CMS OPPS Addendum E — CPT Codes Paid Only as Inpatient Procedures: https://www.cms.gov/medicare/medicare-fee-for-service-payment/hospitaloutpatientpps/downloads/cms-1427-p_adde.pdf
03CMS Manual System Pub 100-04 Transmittal 13575 (I/OCE January 2026): https://www.cms.gov/files/document/r13575cp.pdf
04HHS CMS Manual System r13162cp — HCPCS Code Descriptions including 21423: https://www.hhs.gov/guidance/sites/default/files/hhs-guidance-documents/CMS/r13162cp.pdf

Mira Scribe

Mira's AI scribe captures the fracture classification (palatal vs. maxillary), fragment count, degree of displacement, fixation method by name (e.g., titanium plate and screw, external fixation), and any concurrent craniofacial structures addressed. This prevents the most common audit flag for 21423: an operative note that describes open exposure but omits the complexity elements that distinguish it from 21422, leaving coders unable to defend the higher-level code.

See how Mira captures CPT 21423 documentation