ICD-10-CM 2027 diagnosis code
G20.CParkinsonism, unspecified
G20.C is a valid, billable ICD-10-CM code for parkinsonism, unspecified. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Looking up by condition? See ICD-10 code for Parkinsonism, ICD-10 code for Hemiparkinsonism, ICD-10 code for Pyramidopallidonigral syndrome.
Code last changed in FY2024 (effective October 1, 2023). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About G20.C
G20.C is the ICD-10-CM diagnosis code for parkinsonism, unspecified. It belongs to category G20 (Parkinson's disease), block G20-G26 (extrapyramidal and movement disorders) and chapter 6 (diseases of the nervous system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
Within G20, choose G20.C (Parkinsonism, unspecified) only when documentation doesn't support a more specific option: without dyskinesia (G20.A) and with dyskinesia (G20.B).
Don't report G20.C together with the conditions in its Excludes1 note: Parkinson's disease NOS (G20.A1), Parkinson's disease with dyskinesia (G20.B-), Parkinson's disease without dyskinesia (G20.A-) and secondary parkinsonism (G21.-).
Use an additional code, if applicable, to identify: dementia with anxiety (F02.84, F02.A4, F02.B4, F02.C4), dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-), dementia with mood disturbance (F02.83, F02.A3, F02.B3, F02.C3), dementia with psychotic disturbance (F02.82, F02.A2, F02.B2, F02.C2), dementia without behavioral disturbance (F02.80, F02.A0, F02.B0, F02.C0) and 1 more.
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 056 (Degenerative Nervous System Disorders with MCC, relative weight 2.2655) and DRG 057 (Degenerative Nervous System Disorders without MCC, relative weight 1.2838), in MDC 01 (Diseases and Disorders of the Nervous System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
It was added in FY2024, effective October 1, 2023.
Coding notes
Notes that apply from higher levels
Instructions written at a parent level also apply to G20.C.
› From G20 Parkinson's disease
- code, if applicable, to identify:
- dementia with anxiety (F02.84, F02.A4, F02.B4, F02.C4)
- dementia with behavioral disturbance (F02.81-, F02.A1-, F02.B1-, F02.C1-)
- dementia with mood disturbance (F02.83, F02.A3, F02.B3, F02.C3)
- dementia with psychotic disturbance (F02.82, F02.A2, F02.B2, F02.C2)
- dementia without behavioral disturbance (F02.80, F02.A0, F02.B0, F02.C0)
- mild neurocognitive disorder due to known physiological condition (F06.7-)
Broader instructions also apply from Chapter 6: Diseases of the nervous system.
Alphabetic index entries
11 entriesTerms in the official ICD-10-CM index that lead to G20.C.
- Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety) › with › Parkinsonism
- Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety) › with › Parkinsonism › with behavioral disturbance
- Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety) › in (due to) › paralysis agitans
- Dementia (degenerative (primary)) (persisting) (unspecified severity) (without behavioral disturbance, psychotic disturbance, mood disturbance, and anxiety) › in (due to) › paralysis agitans › with behavioral disturbance
- Hemiparkinsonism
- Paralysis, paralytic (complete) (incomplete) › agitans
- Parkinsonism (idiopathic) (primary)
- Parkinsonism (idiopathic) (primary) › dementia
- Parkinsonism (idiopathic) (primary) › dementia › with behavioral disturbance
- Pyramidopallidonigral syndrome
- Syndrome › pyramidopallidonigral
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 01 · Diseases and Disorders of the Nervous System
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2024 (effective 10/1/2023): Added
- No changes since FY2024.
Common questions about G20.C
Is G20.C billable?
- Yes. G20.C is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can G20.C be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict G20.C as a principal diagnosis.
Is G20.C a CC or MCC?
- No. G20.C is neither a CC nor an MCC under MS-DRG v44.0.
What DRG does G20.C group to?
- G20.C is used in the MS-DRG v44.0 logic for MS-DRG 056 (Degenerative Nervous System Disorders with MCC) and MS-DRG 057 (Degenerative Nervous System Disorders without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.