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ICD-10-CM 2027 diagnosis code

I1A.0Resistant hypertension

✓ Billable / specific

I1A.0 is a valid, billable ICD-10-CM code for resistant hypertension. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code last changed in FY2024 (effective October 1, 2023). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About I1A.0

I1A.0 is the ICD-10-CM diagnosis code for resistant hypertension. It belongs to category I1A (other hypertension), block I10-I1A (hypertensive diseases) and chapter 9 (diseases of the circulatory system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

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

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 304 (Hypertension with MCC, relative weight 1.2011) and DRG 305 (Hypertension without MCC, relative weight 0.7581), in MDC 05 (Diseases and Disorders of the Circulatory System), 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 was added in FY2024, effective October 1, 2023.

Coding notes

Applicable toConditions and synonyms classified to this code
  • Apparent treatment resistant hypertension
  • Treatment resistant hypertension
  • True resistant hypertension
Code firstSequence the underlying condition first
  • specific type of existing hypertension, if known, such as:
  • essential hypertension (I10)
  • secondary hypertension (I15.-)

Notes that apply from higher levels

Instructions written at a parent level also apply to I1A.0.

Broader instructions also apply from I10-I1A Hypertensive diseases and Chapter 9: Diseases of the circulatory system.

Alphabetic index entries

1 entries

Terms in the official ICD-10-CM index that lead to I1A.0.

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 05 · Diseases and Disorders of the Circulatory System

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
  • FY2024 (effective 10/1/2023): Added
  • No changes since FY2024.

Common questions about I1A.0

Is I1A.0 billable?

Yes. I1A.0 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can I1A.0 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict I1A.0 as a principal diagnosis.

Is I1A.0 a CC or MCC?

No. I1A.0 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does I1A.0 group to?

I1A.0 is used in the MS-DRG v44.0 logic for MS-DRG 304 (Hypertension with MCC) and MS-DRG 305 (Hypertension without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.