ICD-10-CM 2027
ICD-10 code for less than a high school diploma
From the official ICD-10-CM alphabetic index entry “Less than a high school diploma”. Page updated September 29, 2026.
About coding less than a high school diploma
The ICD-10-CM code for less than a high school diploma is Z55.5 (Less than a high school diploma).
Within Z55 (problems related to education and literacy), Z55.5 is specifically for less than a high school diploma. Related codes cover Illiteracy and low-level literacy (Z55.0), Schooling unavailable and unattainable (Z55.1), failed school examinations (Z55.2), underachievement in school (Z55.3), educational maladjustment and discord with teachers and classmates (Z55.4), problems related to health literacy (Z55.6), other problems related to education and literacy (Z55.8) and unspecified (Z55.9).
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.
Common questions about less than a high school diploma ICD-10 codes
What is the ICD-10 code for less than a high school diploma?
- Z55.5 — Less than a high school diploma.
Is Z55.5 billable?
- Yes. Z55.5 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can Z55.5 be used as a principal diagnosis?
- No. It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.
Is Z55.5 a CC or MCC?
- No. Z55.5 is neither a CC nor an MCC under MS-DRG v44.0.