ICD-10 code G30 is the category-level code for Alzheimer’s disease, covering both senile (late-onset) and presenile (early-onset) forms of this progressive neurodegenerative disorder. G30 is not used alone — it functions as an etiology code and must always be paired with a secondary F02 manifestation code to capture the associated dementia. Correct application of G30 requires coders to understand onset age, dementia severity, and behavioral disturbances, all of which directly affect code specificity, reimbursement, and audit defensibility.
What Does ICD-10 Code G30 Mean?
ICD-10-CM G30 classifies Alzheimer’s disease — a chronic, irreversible neurodegenerative condition that progressively destroys memory, cognitive function, and ultimately the ability to perform daily activities. The G30 category includes both the classic senile form (onset after age 65) and the rarer presenile form (onset before age 65, sometimes as early as age 30).
Key attributes of category G30:
- Not independently billable — G30 must always be reported with a companion F02 dementia code
- Covers senile and presenile forms of Alzheimer’s dementia
- Applicable to adult patients aged 15–124 years
- Falls under Chapter 6 (Diseases of the Nervous System) of ICD-10-CM
- Governed by the etiology/manifestation convention, which dictates sequencing order
What Conditions and Diagnoses Does G30 Cover?
Category G30 captures Alzheimer’s disease in its documented clinical forms. It includes:
- Alzheimer’s dementia with early onset (G30.0) — onset before the mid-60s, often with genetic markers such as APOE-e4
- Alzheimer’s dementia with late onset (G30.1) — onset after the mid-60s, the most common presentation
- Other Alzheimer’s disease (G30.8) — atypical or variant presentations not classified elsewhere
- Alzheimer’s disease, unspecified (G30.9) — used only when documentation does not specify onset type
What Does G30 Specifically Exclude?
The G30 category carries an Excludes1 note — meaning these codes must never be reported simultaneously with G30:
- Senile degeneration of brain NEC (G31.1)
- Senile dementia NOS (F03.–)
- Senility NOS (R41.81)
These Excludes1 conditions represent clinically distinct presentations and cannot co-exist with a confirmed Alzheimer’s diagnosis on the same claim.
When Is G30 the Right Code to Use?
G30 applies when the treating provider has documented a confirmed Alzheimer’s disease diagnosis — not merely cognitive decline, memory loss, or age-related changes. Use the following criteria to validate code selection:
- Confirm the provider has explicitly documented “Alzheimer’s disease” — query-level language like “dementia, possibly Alzheimer’s type” is insufficient for outpatient coding
- Identify the onset type — review clinical notes, neuropsychological evaluations, and patient history for age of symptom onset
- Select the appropriate G30 subcode — G30.0 (early onset), G30.1 (late onset), G30.8 (other), or G30.9 (unspecified)
- Select the companion F02 code — review documentation for dementia severity (mild, moderate, severe) and behavioral features (behavioral disturbance, psychotic disturbance, mood disturbance, anxiety, or none)
- Sequence G30 first, F02 second — per the etiology/manifestation convention, the underlying disease always leads
How Does G30 Differ From F03 (Unspecified Dementia)?
| Feature | G30.– (Alzheimer’s Disease) | F03.– (Unspecified Dementia) |
|---|---|---|
| Provider must document | Confirmed “Alzheimer’s disease” | Dementia without specified etiology |
| Requires companion code | Yes — F02.– always required | No — F03 is standalone |
| Etiology known | Yes — Alzheimer’s pathology | No — etiology undetermined |
| Appropriate when | Diagnosis explicitly stated | Etiology unclear or not documented |
| Audit risk if misused | High — claim may be downcoded | Moderate — may miss specificity |
In practice, coders frequently encounter providers who document “dementia” without specifying Alzheimer’s. In these cases, G30 cannot be assumed — F03 is the correct choice unless the provider clarifies the diagnosis through a query response.
What Documentation Is Required to Support G30?
Coding Alzheimer’s disease to the highest degree of specificity requires reviewing multiple documentation elements. Incomplete records are the most common driver of G30 coding errors and payer denials.
What Must the Provider Document in the Clinical Notes?
The following elements must be present to support G30 and the companion F02 code:
- Explicit diagnosis of Alzheimer’s disease — stated using those exact terms or a recognized clinical equivalent (e.g., “primary degenerative dementia, Alzheimer type”)
- Onset age or type — supports selection of G30.0 vs. G30.1; “presenile” or “senile onset” are acceptable clinical equivalents
- Dementia severity — mild, moderate, or severe, supported by cognitive assessment scores (MMSE, MoCA, CDR scale)
- Behavioral and psychiatric features — explicit documentation of behavioral disturbance, psychotic features (hallucinations, delusions), mood disturbance, or anxiety if any are present
- Absence of behavioral disturbance — when no behavioral features are present, the provider should document this to support the “without behavioral disturbance” F02 variant
Which Diagnostic or Lab Results Support This Code?
Supporting clinical evidence that strengthens documentation:
- MRI or CT brain imaging showing cortical atrophy, hippocampal atrophy, or reduced medial temporal lobe volume
- Neuropsychological testing (MMSE, MoCA, CDR) with documented scores and date of assessment
- PET scan or amyloid imaging results, where available
- Cerebrospinal fluid (CSF) biomarkers — Aβ42, tau, and phospho-tau levels
- Genetic testing results (APOE-e4 status) for early-onset cases
- Clinical progression notes confirming deterioration over time
What Is the Documentation Standard for Inpatient vs. Outpatient Settings?
| Setting | Documentation Standard | Code Assignment Rule |
|---|---|---|
| Inpatient | Physician may document “possible” or “probable” Alzheimer’s — still codeable | Code as confirmed per UHDDS inpatient guidelines |
| Outpatient | Only code confirmed diagnoses — “probable” or “possible” not coded | Query provider or use signs/symptoms codes |
| Skilled Nursing / Long-Term Care | Requires active problem list and MDS documentation | G30 may drive care planning and resource intensity |
How Does G30 Affect Medical Billing and Claims?
G30 drives significant revenue cycle implications because Alzheimer’s disease is a chronic, progressive condition requiring complex care management. Key billing considerations:
- G30 is grouped into MS-DRG 056 (Degenerative nervous system disorders with MCC) or MS-DRG 057 (without MCC) for inpatient claims
- The companion F02 code, not G30, often drives the principal diagnosis determination for outpatient encounters
- Behavioral disturbance subcodes (F02.81–, F02.B1–, etc.) frequently affect risk adjustment scoring under Medicare Advantage and ACO models
- Dementia-related diagnoses are used in hierarchical condition category (HCC) risk scoring — specificity directly affects capitation payments
What CPT or Procedure Codes Are Commonly Billed With G30?
| CPT Code | Description | Typical Pairing Context |
|---|---|---|
| 99213–99215 | Office or outpatient E&M visits | Routine neurology or primary care follow-up |
| 96132–96133 | Neuropsychological testing, administration | Initial diagnosis workup or severity staging |
| 96136–96137 | Psychological/neuropsychological testing, evaluation | Cognitive assessment documentation |
| 70553 | MRI brain with contrast | Structural imaging to support diagnosis |
| 78816 | PET scan, whole body | Amyloid PET for early-onset cases |
| G0505 | Cognitive impairment assessment, Medicare | Applicable for Medicare Annual Wellness Visit add-on |
Are There Any Prior Authorization or Coverage Restrictions?
- Medicare covers neuropsychological testing (96132–96133) under LCD L33380 when medical necessity is documented — G30 supports this
- Amyloid PET scans (78816) are covered under Medicare’s Coverage with Evidence Development (CED) program via approved clinical trials; routine billing is limited
- Behavioral health services related to dementia management may require separate authorization under behavioral carve-out plans
- Medicare Advantage plans may apply additional prior authorization requirements for cognitive testing and specialist referrals
What Coding Errors Should You Avoid With G30?
The G30 category generates some of the most frequently audited claims in outpatient neurology and primary care. The top errors, ranked by audit frequency:
- Reporting G30 without a companion F02 code — the most common error; G30 alone will often trigger a claim edit or denial
- Defaulting to G30.9 (unspecified) when onset is documented — if the record contains age of onset or clinical notes indicating presenile vs. senile, specificity is required
- Selecting the wrong F02 behavioral subcode — coders sometimes apply F02.81– (behavioral disturbance) when the provider only documents agitation, without distinguishing this as a behavioral vs. psychotic feature
- Using G30 for “probable Alzheimer’s” in outpatient settings — outpatient coding rules prohibit this; query the provider or code signs and symptoms instead
- Failing to update the F02 subcode as severity progresses — a patient coded as mild (F02.A–) at one visit should be re-evaluated at subsequent encounters as disease advances
What Do Auditors Look for When Reviewing Claims With G30?
- Missing or inconsistent F02 companion code
- F02 behavioral disturbance subcode applied without corresponding clinical documentation of the behavior
- Onset type inconsistent with patient age (e.g., G30.1 late onset coded for a 52-year-old)
- Cognitive assessment scores absent from the record despite coding “moderate” or “severe” severity
- Alzheimer’s coded in outpatient setting as “probable” without provider confirmation
How Does G30 Relate to Other ICD-10 Codes?
| Related Code | Relationship Type | Key Distinction |
|---|---|---|
| F02.– (Dementia in diseases classified elsewhere) | Required companion — manifestation | Always sequenced second after G30; captures dementia severity and behavioral features |
| F03.– (Unspecified dementia) | Mutually exclusive | Used when etiology is not established; never reported with G30 |
| G31.1 (Senile degeneration of brain NEC) | Excludes1 | Distinct condition; cannot be reported with G30 |
| F05 (Delirium) | Use additional | Reported when delirium is superimposed on Alzheimer’s dementia |
| F01.– (Vascular dementia) | Possible co-occurrence | Per Excludes2 note under F02, vascular dementia may be reported alongside G30+F02 if separately documented |
| F06.7– (Mild neurocognitive disorder) | Use additional, if applicable | Reported in early-stage disease when documented separately by provider |
| Z84.3 (Family history of dementia) | Supplementary | Used as additional code for risk factor documentation |
What Is the Correct Code Sequencing When G30 Appears With Other Diagnoses?
- G30.– always sequences first as the etiology under the etiology/manifestation convention
- F02.– sequences immediately after G30 to capture the dementia manifestation with full specificity
- F05 (delirium) is listed as an additional code if superimposed delirium is documented
- Any additional behavioral or psychiatric F02 subcodes are reported after the primary F02 selection if multiple behavioral features are present
- Comorbid conditions (hypertension, diabetes, etc.) follow the neurocognitive codes in sequencing for outpatient encounters where Alzheimer’s is the reason for the visit
Real-World Coding Scenario — How G30 Is Applied in Practice
A 74-year-old male presents to his neurologist for a follow-up visit. The physician’s note documents: “Patient has late-onset Alzheimer’s disease, moderate severity. MMSE score 16/30. Wife reports increased agitation and nighttime wandering over the past two months. No psychotic features noted. Continue memantine 20mg daily.”
Correct Code Application
- G30.1 — Alzheimer’s disease with late onset (onset after mid-60s; explicitly documented)
- F02.A1 — Major neurocognitive disorder in other diseases classified elsewhere, moderate, with behavioral disturbance (agitation and wandering = behavioral disturbance; moderate severity confirmed by MMSE)
- G30.1 sequenced first, F02.A1 sequenced second
Common Mistake in This Scenario
- Incorrect code: G30.9 + F02.80 (unspecified, without behavioral disturbance)
- Why it fails: G30.9 is inappropriate because onset type is explicitly documented as late. F02.80 fails to capture the documented behavioral disturbance (agitation and wandering), which affects HCC risk scoring and may trigger a query from a Medicare Advantage plan
Frequently Asked Questions About ICD-10 Code G30
Is ICD-10 Code G30 Valid for Use in 2026?
ICD-10 category G30 remains valid and billable for fiscal year 2026 with no changes to its core structure or description. The subcodes G30.0, G30.1, G30.8, and G30.9 are all currently active. Coders should verify annually against the ICD-10-CM Official Coding Guidelines released by CMS each October to confirm no updates have been applied.
Can I Report G30 Without a Companion F02 Code?
No — G30 cannot be reported as a standalone code. The etiology/manifestation convention in ICD-10-CM requires G30 to be sequenced first, followed by the appropriate F02 dementia code. Claims submitted with G30 alone will often fail claim edits and result in denials or requests for additional documentation.
When Should I Use G30.9 Instead of G30.0 or G30.1?
G30.9 (Alzheimer’s disease, unspecified) should only be used when the provider’s documentation does not indicate whether the disease is early or late onset. If the patient’s age of symptom onset, clinical notes, or imaging reports indicate a presenile or senile onset, the more specific subcode is required. Defaulting to G30.9 when onset information is available is a coding specificity error that may be flagged during audit.
What Is the Difference Between G30 and F03 (Unspecified Dementia)?
G30 requires a confirmed provider diagnosis of Alzheimer’s disease as the underlying etiology of the dementia. F03 is appropriate when the provider documents dementia without identifying a specific cause. These two code categories are mutually exclusive — F03 is never reported alongside G30.
Does Behavioral Disturbance Have to Be Explicitly Documented to Use the F02.81– Subcodes?
Yes — the behavioral disturbance subcodes (F02.81–, F02.A1–, F02.B1–, F02.C1–) require that specific behavioral features be documented in the clinical record. Behaviors such as agitation, aggression, wandering, disinhibition, and sleep disturbance qualify. Coders should not infer behavioral disturbance from the diagnosis alone — documentation must explicitly describe the behavior.
How Is Alzheimer’s Disease Coded When Delirium Is Also Present?
When a patient with Alzheimer’s disease develops superimposed delirium, coders report G30.– first, followed by the appropriate F02.– code, and then F05 (Delirium due to known physiological condition) as an additional code. The ICD-10-CM tabular list includes F05 in the “use additional code, if applicable” instruction under G30.
Is There a Specific ICD-10 Code for Early-Onset Familial Alzheimer’s Disease?
Early-onset familial Alzheimer’s disease with a known genetic basis (such as mutations in PSEN1, PSEN2, or APP) is coded to G30.0 (Alzheimer’s disease with early onset). There is no separate ICD-10-CM code for the familial or genetic subtype. Coders may also report Z84.3 (Family history of dementia) as a supplementary code when relevant.
Key Takeaways
- G30 is the etiology code for Alzheimer’s disease — it always requires a companion F02 code and must be sequenced first
- Select the most specific G30 subcode available: G30.0 (early), G30.1 (late), G30.8 (other), or G30.9 (unspecified only when onset is truly undocumented)
- The F02 companion code must reflect dementia severity (mild, moderate, severe) and behavioral features (behavioral disturbance, psychotic disturbance, mood disturbance, anxiety, or none)
- In outpatient settings, only code confirmed Alzheimer’s diagnoses — “probable” or “possible” language does not meet the coding threshold
- Behavioral disturbance subcodes have direct revenue cycle impact through HCC risk adjustment under Medicare Advantage
- The most common audit triggers are missing F02 codes, incorrect behavioral subcode selection, and G30.9 defaults when onset is documented
- Auditors commonly flag claims where cognitive assessment scores (MMSE, MoCA) are absent but severity subcodes have been applied
For deeper guidance on this and related conditions, refer to the ICD-10-CM Official Coding Guidelines, AHA Coding Clinic advisories on dementia coding, and CMS LCD resources for neuropsychological testing coverage.
Sources:
- CMS ICD-10-CM Official Coding Guidelines: https://www.cms.gov/medicare/coding-billing/icd-10-codes
- WHO ICD-10 Reference Classification: https://www.who.int/standards/classifications/classification-of-diseases
- AHA Coding Clinic guidance on dementia and neurodegenerative disorders
- CDC Alzheimer’s Disease and Healthy Aging Data: https://www.cdc.gov/aging/agingdata/index.html