Alphabetic Index FY2027

I1A.0

Resistant hypertension

FY2027Chapter 9: Diseases of the circulatory system/I10–I1A Hypertensive diseases

BillableComplete code, valid to report
Care settingsHome Health Primary · MMTA - Cardiac and Circulatory

I1A.0 (also written I1A0) is a billable ICD-10-CM diagnosis code for resistant hypertension. It is part of the FY2027 code set, effective October 1, 2026. The Alphabetic Index lists it under 1 entry. Its coding notes include a Code first instruction, a Use additional code instruction, 2 Excludes1 entries and 11 Excludes2 entries.

Guidelines tip

From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.

I1A.0 is an additional code, used when the provider documents resistant hypertension. The specific type of hypertension is sequenced first, if known.

Guidelines I.C.9.a.12Resistant hypertensionRead the official text

Code first

If the underlying condition listed here is present and known, sequence it first.

This code
  • specific type of existing hypertension, if known, such as:
    • essential hypertension (I10)
    • secondary hypertension (I15.-)

Use additional code

Add the listed code as a secondary code, if known.

Also from chapter/block level (6 notes)
Inherited from I10–I1A Hypertensive diseases
  • code to identify:
    • exposure to environmental tobacco smoke (Z77.22)
    • history of tobacco dependence (Z87.891)
    • occupational exposure to environmental tobacco smoke (Z57.31)
    • tobacco dependence (F17.-)
    • tobacco use (Z72.0)

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Also from chapter/block level (2 notes)
Inherited from I10–I1A Hypertensive diseases
  • neonatal hypertension (P29.2)
  • primary pulmonary hypertension (I27.0)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Also from chapter/block level (11 notes)
Inherited from I10–I1A Hypertensive diseases
  • hypertensive disease complicating pregnancy, childbirth and the puerperium (O10-O11, O13-O16)
Inherited from Chapter 9 Diseases of the circulatory system
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
  • systemic connective tissue disorders (M30-M36)
  • transient cerebral ischemic attacks and related syndromes (G45.-)

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

Home Health Primary

Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Cardiac and Circulatory clinical group.

Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026

Inclusion terms

Conditions classified to this code.

This code
  • Apparent treatment resistant hypertension
  • Treatment resistant hypertension
  • True resistant hypertension

Alphabetic Index terms

Terms the official Alphabetic Index lists for this code. 1 entry