Excludes1 pair
G20- vs G20.C
G20 and G20.C are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.
The official note, declared on G20.C
Parkinson's disease with dyskinesia (G20.B-)
G20
Parkinson's disease
Not billable
- Chapter 6
- Diseases of the nervous system
- Section
- G20-G26
Use when the record says
- Hemiparkinsonism
- Idiopathic Parkinsonism or Parkinson's disease
- Paralysis agitans
- Primary Parkinsonism or Parkinson's disease
G20.C
Parkinsonism, unspecified
BillableUnspecified
- Chapter 6
- Diseases of the nervous system
- Section
- G20-G26
Use when the record says
- Parkinsonism, NOS
Indexed under
- Hemiparkinsonism
- Parkinsonism (idiopathic) (primary)
- Pyramidopallidonigral syndrome
- Paralysis, paralytic › agitans
- Parkinsonism › dementia
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027