Z55.0 Illiteracy and low-level literacy

The ICD-10-CM code for Illiteracy and low-level literacy is Z55.0 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

21: Factors influencing health status and contact with health services (Z00-Z99)

Section

Z55-Z65: Persons with potential health hazards related to socioeconomic and psychosocial circumstances (Z55-Z65)

Category Z55

10 codes (9 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to Z55.0:

• Illiteracy
• Low › level of literacy
• Problem (with) (related to) › illiteracy
• Problem (with) (related to) › literacy › low level

U.S. Hospital Utilization

• An estimated 2,190 U.S. inpatient stays in 2023 included Z55.0 among the documented diagnoses.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

SDOH codes may be based on non-provider clinician documentation

For social determinants of health classified to chapter 21, such as information found in categories Z55-Z65, Persons with potential health hazards related to socioeconomic and psychosocial circumstances, code assignment may be based on medical record documentation from clinicians involved in the care of the patient who are not the patient’s provider since this information represents social information, rather than medical diagnoses. For example, coding professionals may utilize documentation of social information from social workers, community health workers, case managers, or nurses, if their documentation is included in the official medical record.

Unlabeled Z code list + cross-reference to I.B.14

Z76.3 Healthy person accompanying sick person Z76.4 Other boarder to healthcare facility Z76.5 Malingerer [conscious simulation] Z91.1- Patient’s noncompliance with medical treatment and regimen Z91.A- Caregiver’s noncompliance with patient’s medical treatment and regimen Z91.B Personal risk factor of exposure to diethylstilbestrol Z91.83 Wandering in diseases classified elsewhere Z91.84- Oral health risk factors Z91.89 Other specified personal risk factors, not elsewhere classified See Section I.B.14. for Z55-Z65 Persons with potential health hazards related to socioeconomic and psychosocial circumstances, documentation by clinicians other than the patient’s provider

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)