CPT code 20931: Spinal bone graft, structural allograft2026 Medicare rate & RVUs in California
Report 20931 with spine surgery when a surgeon implants structural donor bone as support, rather than morselized graft material.
CMS doesn’t publish an office rate for 20931 in California.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
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On this page 9 sections
What 20931 covers
CPT 20931 captures placement of a shaped, donor-derived bone graft that provides structural support during spinal reconstruction or fusion. Unlike chips or granules used to fill a fusion bed, this graft retains a block or strut form and may help maintain spacing or support between vertebrae. A spine surgeon typically places it during an operative spinal fusion, such as an interbody fusion, in a hospital or ambulatory surgical setting. The graft is allograft tissue, not bone harvested from the patient during the operation.
Report 20931 only alongside an eligible primary spine procedure; it is an add-on, not a stand-alone service. The operative report should identify the structural allograft and its role in the spinal reconstruction, distinguishing it from morselized allograft and structural autograft. CMS pays this add-on within the primary procedure’s global period.
This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.
Where 20931 pays more and less in California
The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.
29 of 29 payment localities
| Payment locality | Office | Facility |
|---|---|---|
| Bakersfield, CA | Unavailable | $93.50 |
| Chico, CA | Unavailable | $91.95 |
| El Centro, CA | Unavailable | $92.04 |
| Fresno, CA | Unavailable | $91.95 |
| Hanford, CA | Unavailable | $91.95 |
| Los Angeles, CA | Unavailable | $97.59 |
| Madera, CA | Unavailable | $91.95 |
| Marin County, CA | Unavailable | $101.20 |
| Merced, CA | Unavailable | $91.95 |
| Modesto, CA | Unavailable | $91.95 |
| Napa, CA | Unavailable | $98.47 |
| Oxnard, CA | Unavailable | $96.00 |
| Redding, CA | Unavailable | $91.95 |
| Rest of California | Unavailable | $91.95 |
| Riverside, CA | Unavailable | $98.25 |
| Sacramento, CA | Unavailable | $94.38 |
| Salinas, CA | Unavailable | $94.01 |
| San Benito County, CA | Unavailable | $104.23 |
| San Diego, CA | Unavailable | $94.80 |
| San Francisco, CA | Unavailable | $100.53 |
| San Luis Obispo, CA | Unavailable | $92.79 |
| Santa Clara County, CA | Unavailable | $101.49 |
| Santa Cruz, CA | Unavailable | $94.53 |
| Santa Maria, CA | Unavailable | $93.97 |
| Santa Rosa, CA | Unavailable | $95.31 |
| Stockton, CA | Unavailable | $91.95 |
| Vallejo, CA | Unavailable | $97.51 |
| Visalia, CA | Unavailable | $91.95 |
| Yuba City, CA | Unavailable | $91.95 |
How the 20931 rate is calculated
Each of 20931’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.
How the rate is built · 20931
RVUs × geographic indexes × conversion factor
Work1.76
1.76 RVUs× 1.000 GPCI
Practice expense0.59
0.59 RVUs× 1.000 GPCI
Malpractice0.59
0.59 RVUs× 1.000 GPCI
Adjusted RVUs
2.9400
Conversion factor
$33.4009
Medicare rate
$98.20
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 20931
The CMS indicators that decide how 20931 is paid alongside other services.
CMS payment indicators · 20931
Spinal bone graft, structural allograft
| Rule | CMS value | What it means |
|---|---|---|
| Global period | ZZZ | Add-on code: falls within the primary procedure’s global period. |
| Multiple procedures | 0 | No multiple-procedure reduction. |
| Bilateral (modifier 50) | 0 | The 150% bilateral adjustment doesn’t apply. |
| Assistant at surgery (80/81/82/AS) | 1 | Not paid (statutory restriction). |
| Co-surgeons (62) | 1 | Permitted with supporting documentation. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 0 | Physician service: no professional/technical split. |
20931 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 20930Spinal graft materialMorselized allograft
- Choose 20931 for structural donor bone used as support; choose 20930 for morselized donor bone used as graft material.
- 20938Spinal bone graftStructural autograft, separate incision
- Both involve structural grafting during spine surgery. The source differs: 20931 is donor bone, while 20938 is bone harvested from the patient.
- 20936Spinal autograftLocal, same incision
- 20936 describes local bone from the operative site used as graft material. It is not the structural donor-bone service reported with 20931.
20931 billing questions
Can 20931 be reported without a primary spine procedure?
No. It is an add-on code and must be reported with a primary procedure.
How does 20931 differ from 20930?
20931 represents structural donor bone used as a supporting graft. Code 20930 is for morselized donor bone, such as chips or granules used to fill a fusion bed.
How does 20931 differ from 20938?
Both describe structural grafting for spine surgery, but 20931 is for donor bone and 20938 is for bone graft taken from the patient.
What documentation supports reporting 20931?
The operative report should identify the donor-derived graft as structural and describe its placement and role in the spinal reconstruction.
How does CMS treat payment for 20931?
CMS treats it as an add-on paid within the primary procedure’s global period.
Where these rates come from
FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.
CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027
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