---
title: "ICD-10-CM I48.91: Unspecified atrial fibrillation | BillingBrief"
description: "ICD-10-CM code I48.91: Unspecified atrial fibrillation. Category, related codes, and the official source, in plain English."
canonical: "https://billingbrief.com/icd10/i48.91/"
language: "en"
---

# I48.91 Unspecified atrial fibrillation

ICD-10-CM · [CMS code reference](#source)

**Official ICD-10-CM description:** Unspecified atrial fibrillation

## Related codes

-   [`I48.0` Paroxysmal atrial fibrillation ICD-10-CM](https://billingbrief.com/icd10/i48.0/)
-   [`I48.11` Longstanding persistent atrial fibrillation ICD-10-CM](https://billingbrief.com/icd10/i48.11/)
-   [`I48.19` Other persistent atrial fibrillation ICD-10-CM](https://billingbrief.com/icd10/i48.19/)
-   [`I48.20` Chronic atrial fibrillation, unspecified ICD-10-CM](https://billingbrief.com/icd10/i48.20/)
-   [`I48.21` Permanent atrial fibrillation ICD-10-CM](https://billingbrief.com/icd10/i48.21/)
-   [`I48.3` Typical atrial flutter ICD-10-CM](https://billingbrief.com/icd10/i48.3/)
-   [`I48.4` Atypical atrial flutter ICD-10-CM](https://billingbrief.com/icd10/i48.4/)
-   [`I48.92` Unspecified atrial flutter ICD-10-CM](https://billingbrief.com/icd10/i48.92/)

## Common questions

### Is I48.91 a billable code?

Yes. I48.91 is a billable ICD-10-CM code in the ICD-10-CM FY2027 (effective October 1, 2026) code set.

## From the source

Official description from [CMS](https://www.cms.gov/medicare/coding-billing/icd-10-codes).
ICD-10-CM FY2027 (effective October 1, 2026).

Code set

ICD-10-CM

Category

I48 Atrial fibrillation and flutter

Chapter

Diseases of the circulatory system

Billable

Yes

Educational reference only. Not medical, legal, or billing advice. Always check the current official code set and payer policy before you bill. [About BillingBrief and our sources](https://billingbrief.com/about/).