ICD-10-CM 2027
ICD-10 code for Flatback syndrome
From the official ICD-10-CM alphabetic index entry “Flatback syndrome”. Page updated September 29, 2026.
About coding Flatback syndrome
The ICD-10-CM code for Flatback syndrome is M40.30 (Flatback syndrome, site unspecified). The official index lists 3 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on M40.30.
Within M40.3, choose M40.30 (site unspecified) only when documentation doesn't support a more specific option: thoracolumbar region (M40.35), lumbar region (M40.36) and lumbosacral region (M40.37).
Code first: underlying disease.
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
More specific Flatback syndrome codes (official index)
Common questions about Flatback syndrome ICD-10 codes
What is the ICD-10 code for Flatback syndrome?
- M40.30 — Flatback syndrome, site unspecified. More specific codes apply when the documentation supports them: M40.36, M40.37, M40.35.
What is the ICD-10 code for lumbar region flatback syndrome?
- M40.36 — Flatback syndrome, lumbar region.
What is the ICD-10 code for lumbosacral region flatback syndrome?
- M40.37 — Flatback syndrome, lumbosacral region.
What is the ICD-10 code for thoracolumbar region flatback syndrome?
- M40.35 — Flatback syndrome, thoracolumbar region.
Is M40.30 billable?
- Yes. M40.30 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can M40.30 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict M40.30 as a principal diagnosis.
Is M40.30 a CC or MCC?
- No. M40.30 is neither a CC nor an MCC under MS-DRG v44.0.