2027 ICD-10-CM Diagnosis Code I1A.0Resistant hypertension

ICD-10-CM Codes›I00–I99›I10-I1A›I1A

ICD-10-CM I1A.0
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

I1A.0 is a billable ICD-10-CM diagnosis code for resistant hypertension. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 304 through 305. Coders also document this condition as hypertension resistant to drug therapy. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Hypertension with complications and secondary hypertension.

I1A.0 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 187 for payment year 2027.

This medical diagnosis code is frequently used in Family Practice medical specialties to designate conditions such hypertension.

Code Identity

ICD-10-CM Code
I1A.0
Billable Status
Yes — Valid for Submission
Code Describes
Resistant hypertension
Short Description
Resistant hypertension
Same as the full description in the CMS dataset.
Parent Code
I1A
Other hypertension

Code Classification

ChapterI00–I99Diseases of the circulatory system
SectionI10-I1AHypertensive diseases
CategoryI1AOther hypertension
This CodeI1A.0Resistant hypertension

Medicare Risk Adjustment (HCC)Billing

I1A.0 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model, but it maps to payment categories in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
no payment category in the model that pays 100% of MA risk scores
Prior Model (CMS-HCC V24)
Not mapped under V24
this diagnosis newly risk-adjusts under the V28 model
Part D (RxHCC)
RxHCC 187 — Hypertension
also risk-adjusts in the Part D prescription drug model (V08)

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Hypertension resistant to drug therapy

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to I1A.0: its own notes plus those printed at block I10-I1A and Chapter 9. A note printed at a category, block or chapter applies to every code under it.

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Apparent treatment resistant hypertension
  • Treatment resistant hypertension
  • True resistant hypertension

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Block I10-I1A Hypertensive diseases applies to 18 codes
  • neonatal hypertension (P29.2)
  • primary pulmonary hypertension (I27.0)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Block I10-I1A Hypertensive diseases applies to 18 codes
  • hypertensive disease complicating pregnancy, childbirth and the puerperium (O10-O11, O13-O16)
From Chapter 9 (I00-I99) Diseases of the circulatory system applies to 1,433 codes
  • 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.-)

Code First

The underlying condition named in the note is sequenced before this code.

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

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Block I10-I1A Hypertensive diseases applies to 18 codes
  • 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)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name I1A.0, its category, or a range that includes it.

Use Additional Code 2

These codes say to use an additional code from the note, and I1A.0 is one of the codes named.

  • G31.84 Mild cognitive impairment of uncertain or unknown etiology
    hypertension (I10-I1A) names I10-I1A, which includes this code
  • Block I60-I69 Cerebrovascular diseases
    hypertension (I10-I1A) names I10-I1A, which includes this code

Code Also 3

These codes say I1A.0 may also be needed to fully describe the condition. The note gives no sequencing direction.

  • I16 Hypertensive crisis
    any identified hypertensive disease (I10-I15, I1A) names I1A, which includes this code
  • Block I20-I25 Ischemic heart diseases
    the presence of hypertension (I10-I1A) names I10-I1A, which includes this code
  • Z15.3 Genetic susceptibility to kidney disease
    if applicable, hypertension (I10-I1A) names I10-I1A, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR CIR008
Hypertension with complications and secondary hypertension
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

High Blood Pressure

Blood pressure is the force of your blood pushing against the walls of your arteries. Each time your heart beats, it pumps blood into the arteries. Your blood pressure is highest when your heart beats, pumping the blood. This is called systolic pressure. When your heart is at rest, between beats, your blood pressure falls.

The full article covers:

  • What is blood pressure?
  • How is high blood pressure diagnosed?
  • What are the different types of high blood pressure?
  • Why do I need to worry about high blood pressure?
  • What are the treatments for high blood pressure?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Code History & ChangesHistory

Replacement I1A.0 replaces the following previously assigned code(s):

  • I10 - Essential (primary) hypertension
  • I11 - Hypertensive heart disease
  • I11.0 - Hypertensive heart disease with heart failure
  • I11.9 - Hypertensive heart disease without heart failure
  • I12 - Hypertensive chronic kidney disease
  • I12.0 - Hyp chr kidney disease w stage 5 chr kidney disease or ESRD
  • I12.9 - Hypertensive chronic kidney disease w stg 1-4/unsp chr kdny
  • I13 - Hypertensive heart and chronic kidney disease
  • I13.0 - Hyp hrt & chr kdny dis w hrt fail and stg 1-4/unsp chr kdny
  • I13.1 - Hypertensive heart and chronic kidney disease w/o hrt fail
  • I13.10 - Hyp hrt & chr kdny dis w/o hrt fail, w stg 1-4/unsp chr kdny
  • I13.11 - Hyp hrt and chr kdny dis w/o hrt fail, w stg 5 chr kdny/ESRD
  • I13.2 - Hyp hrt & chr kdny dis w hrt fail and w stg 5 chr kdny/ESRD
  • I15 - Secondary hypertension
  • I15.0 - Renovascular hypertension
  • I15.1 - Hypertension secondary to other renal disorders
  • I15.2 - Hypertension secondary to endocrine disorders
  • I15.8 - Other secondary hypertension
  • I15.9 - Secondary hypertension, unspecified
FY 2024AddedAdded to the ICD-10-CM code setEffective October 1, 2023.
FY 2025–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About I1A.0Overview

What is the ICD-10 code for resistant hypertension?

The ICD-10-CM code for resistant hypertension is I1A.0 (sometimes written as I1A0). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is I1A.0 (Other hypertension) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report resistant hypertension on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does I1A.0 group to?

When resistant hypertension is the principal diagnosis on an inpatient stay, it groups to MS-DRG 305, 304, with relative weights from 0.7579 to 1.2010 depending on complications. Higher weights mean higher Medicare reimbursement.

Can I1A.0 be reported with P29.2?

Not as a rule. The Excludes1 note at block I10-I1A, which applies to I1A.0, lists "neonatal hypertension (P29.2)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

What is coded first with I1A.0?

The Code First note reads: specific type of existing hypertension, if known, such as: essential hypertension (I10); secondary hypertension (I15.-). When one of these applies, it is sequenced before I1A.0.

Does I1A.0 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage: I1A.0 maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 187 (Hypertension).