M13.1 — Monoarthritis, not elsewhere classified

Not billable

Is M13.1 billable?

No — M13.1 is a non-billable header code. M13.1 groups more specific codes and cannot be submitted on a claim. A valid ICD-10-CM code must be reported at the highest level of specificity available in its branch. Select one of the 22 billable codes beneath M13.1.

Billable codes under this header

M13.1 at a glance

Code	M13.1
Description	Monoarthritis, not elsewhere classified
Billable	No — header code
Code set	ICD-10-CM FY2027
Valid for encounters	October 1, 2026 – September 30, 2027

Excludes1 — never code together — inherited from M13

The conditions below can never be reported together with M13.1 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.

arthrosis (M15-M19)
osteoarthritis (M15-M19)

Excludes2 — not included here — inherited from Chapter 13

The conditions below are not part of M13.1, but a patient may have both at the same time. When documentation supports it, M13.1 and the excluded code may both be reported.

arthropathic psoriasis (L40.5-)
certain conditions originating in the perinatal period (P04-P96)
certain infectious and parasitic diseases (A00-B99)
compartment syndrome (traumatic) (T79.A-)
complications of pregnancy, childbirth and the puerperium (O00-O9A)
congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
endocrine, nutritional and metabolic diseases (E00-E88)
injury, poisoning and certain other consequences of external causes (S00-T88)
neoplasms (C00-D49)
symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

What codes fall under M13.1? (8)

How long has M13.1 existed?

M13.1 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.

Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.