Is M05.1 a billable ICD-10-CM code?

No. M05.1 is a non-billable header code. Code to a higher level of specificity using one of its child codes.

Where does M05.1 sit in the tabular list?

Diseases of the musculoskeletal system and connective tissue (M00-M99), in the block Inflammatory polyarthropathies (M05-M14).

What cannot be coded together with M05.1?

M05.1 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 M05.1 (M05) and apply to it just the same.

M05.1

M05.1 — Rheumatoid lung disease with rheumatoid arthritis

Non-billable headerICD-10-CM

M05.1 is a non-billable header ICD-10-CM code for rheumatoid lung disease with rheumatoid arthritis. It cannot be billed on its own: choose one of the more specific child codes below.

Excludes1 inherited from the categories above M05.1

These are not written on M05.1, but they bind it: a note on a category applies to every code beneath it. Billing M05.1 with anything listed here is a denial.

Written on M05 — Rheumatoid arthritis with rheumatoid factor

rheumatic fever (I00)
juvenile rheumatoid arthritis (M08.-)
rheumatoid arthritis of spine (M45.-)

Other codes that can never be billed with M05.1

These codes carry an Excludes1 note pointing at M05.1. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading M05.1 alone.

R76.81Abnormal rheumatoid factor and anti-citrullinated protein antibody without rheumatoid arthritis

Risk adjustment

M05.1 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

M05.1 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 M05.1

9 child codes. Green means billable.

Related codes at this level

Codes that share M05. If M05.1 is not quite right, the correct code is usually one of these.

Questions about M05.1

Is M05.1 a billable ICD-10-CM code?: No. M05.1 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does M05.1 sit in the tabular list?: Diseases of the musculoskeletal system and connective tissue (M00-M99), in the block Inflammatory polyarthropathies (M05-M14).
What cannot be coded together with M05.1?: M05.1 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 M05.1 (M05) and apply to it just the same.