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M40.3

M40.3Flatback syndrome

Non-billable headerICD-10-CM

M40.3 is a non-billable header ICD-10-CM code for flatback syndrome. It cannot be billed on its own: choose one of the more specific child codes below.

Excludes1 inherited from the categories above M40.3

These are not written on M40.3, but they bind it: a note on a category applies to every code beneath it. Billing M40.3 with anything listed here is a denial.

Written on M40 Kyphosis and lordosis

  • congenital kyphosis and lordosis (Q76.4)
  • kyphoscoliosis (M41.-)
  • postprocedural kyphosis and lordosis (M96.-)

Risk adjustment

M40.3 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Code history

M40.3 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.

Code to one of these instead M40.3

4 child codes. Green means billable.

Related codes at this level

Codes that share M40. If M40.3 is not quite right, the correct code is usually one of these.

Questions about M40.3

Is M40.3 a billable ICD-10-CM code?
No. M40.3 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does M40.3 sit in the tabular list?
Diseases of the musculoskeletal system and connective tissue (M00-M99), in the block Deforming dorsopathies (M40-M43).
What cannot be coded together with M40.3?
M40.3 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above M40.3 (M40) and apply to it just the same.
ICD-10-CMFY2026-Apr· effective April 1, 2026

Loaded directly from the CMS/NCHS ICD-10-CM public-domain release — see data sources and our editorial policy. If this page disagrees with the CMS tabular list, this page is wrong. Reference information for professional coders; not medical or billing advice.