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ICD-10-CM 2027 diagnosis code

R46.2Strange and inexplicable behavior

✓ Billable / specific

R46.2 is a valid, billable ICD-10-CM code for strange and inexplicable behavior. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About R46.2

R46.2 is the ICD-10-CM diagnosis code for Strange and inexplicable behavior. It belongs to category R46 (symptoms and signs involving appearance and behavior), block R40-R46 (symptoms and signs involving cognition, perception, emotional state and behavior) and chapter 18 (symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within R46 (symptoms and signs involving appearance and behavior), R46.2 is specifically for Strange and inexplicable behavior. Related codes cover Very low level of personal hygiene (R46.0), Bizarre personal appearance (R46.1), overactivity (R46.3), Slowness and poor responsiveness (R46.4), Suspiciousness and marked evasiveness (R46.5), Undue concern and preoccupation with stressful events (R46.6), Verbosity and circumstantial detail obscuring reason for contact (R46.7) and other symptoms and signs involving appearance and behavior (R46.8).

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 951 (Other Factors Influencing Health Status, relative weight 0.5577), in MDC 23 (Factors Influencing Health Status and Other Contacts with Health Services), 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 has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 799.89 (other ill-defined conditions).

Notes that apply from higher levels

Instructions written at a parent level also apply to R46.2.

› From R46 Symptoms and signs involving appearance and behavior
Excludes1
  • appearance and behavior in schizophrenia, schizotypal and delusional disorders (F20-F29)
  • mental and behavioral disorders (F01-F99)

Broader instructions also apply from R40-R46 Symptoms and signs involving cognition, perception, emotional state and behavior and Chapter 18: Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified.

Alphabetic index entries

2 entries

Terms in the official ICD-10-CM index that lead to R46.2.

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 23 · Factors Influencing Health Status and Other Contacts with Health Services

ICD-9-CM equivalent

Converter →
  • 799.89Other ill-defined conditionsapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about R46.2

Is R46.2 billable?

Yes. R46.2 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can R46.2 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict R46.2 as a principal diagnosis.

Is R46.2 a CC or MCC?

No. R46.2 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does R46.2 group to?

R46.2 is used in the MS-DRG v44.0 logic for MS-DRG 951 (Other Factors Influencing Health Status). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for R46.2?

The CMS General Equivalence Mappings map R46.2 to ICD-9-CM 799.89.