2027 ICD-10-CM Diagnosis Code R56.01Complex febrile convulsions
ICD-10-CM Codes›R00–R99›R50-R69›R56
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 201
- Not Chronic
R56.01 is a billable ICD-10-CM diagnosis code for complex febrile convulsions. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 100 through 101. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 115 closely related codes. As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. Coders also document this condition as complex febrile seizure. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Epilepsy; convulsions.
For Medicare Advantage risk adjustment, R56.01 maps to CMS-HCC Category 201 (Seizure Disorders and Convulsions) under the V28 model, adding a risk factor of about 0.245 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
R56.01 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
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.
- Complex febrile seizure
- Febrile convulsion
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to R56.01: its own notes plus those printed at R56 and Chapter 18. 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.
- Atypical febrile seizure
- Complex febrile seizure
- Complicated febrile seizure
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- status epilepticus (G40.901)
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.
Notes
General instructions on how these codes are used.
- This chapter includes symptoms, signs, abnormal results of clinical or other investigative procedures, and ill-defined conditions regarding which no diagnosis classifiable elsewhere is recorded.
- Signs and symptoms that point rather definitely to a given diagnosis have been assigned to a category in other chapters of the classification. In general, categories in this chapter include the less well-defined conditions and symptoms that, without the necessary study of the case to establish a final diagnosis, point perhaps equally to two or more diseases or to two or more systems of the body. Practically all categories in the chapter could be designated 'not otherwise specified', 'unknown etiology' or 'transient'. The Alphabetical Index should be consulted to determine which symptoms and signs are to be allocated here and which to other chapters. The residual subcategories, numbered .8, are generally provided for other relevant symptoms that cannot be allocated elsewhere in the classification.
- The conditions and signs or symptoms included in categories R00-R94 consist of:
- (a) cases for which no more specific diagnosis can be made even after all the facts bearing on the case have been investigated;
- (b) signs or symptoms existing at the time of initial encounter that proved to be transient and whose causes could not be determined;
- (c) provisional diagnosis in a patient who failed to return for further investigation or care;
- (d) cases referred elsewhere for investigation or treatment before the diagnosis was made;
- (e) cases in which a more precise diagnosis was not available for any other reason;
- (f) certain symptoms, for which supplementary information is provided, that represent important problems in medical care in their own right.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name R56.01, its category, or a range that includes it.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Convulsions (idiopathic) See Also: Seizure(s); R56.9
Seizure (s) See Also: Convulsions; R56.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Seizures, Febrile
seizures that occur during a febrile episode. it is a common condition, affecting 2-5% of children aged 3 months to five years. an autosomal dominant pattern of inheritance has been identified in some families. the majority are simple febrile seizures (generally defined as generalized onset, single seizures with a duration of less than 30 minutes). complex febrile seizures are characterized by focal onset, duration greater than 30 minutes, and/or more than one seizure in a 24 hour period. the likelihood of developing epilepsy (i.e., a nonfebrile seizure disorder) following simple febrile seizures is low. complex febrile seizures are associated with a moderately increased incidence of epilepsy. (from menkes, textbook of child neurology, 5th ed, p784)
Patient EducationClinical
Seizures
Seizures are symptoms of a brain problem. They happen because of sudden, abnormal electrical activity in the brain. When people think of seizures, they often think of convulsions in which a person's body shakes rapidly and uncontrollably. Not all seizures cause convulsions. There are many types of seizures and some have mild symptoms.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert R56.01 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About R56.01Overview
What is the ICD-10 code for complex febrile convulsions?
The ICD-10-CM code for complex febrile convulsions is R56.01 (sometimes written as R5601). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is R56.01 (Febrile convulsions) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report complex febrile convulsions on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does R56.01 group to?
When complex febrile convulsions is the principal diagnosis on an inpatient stay, it groups to MS-DRG 100, 101, with relative weights from 0.8952 to 1.9236 depending on complications. Higher weights mean higher Medicare reimbursement.
Is R56.01 a CC or MCC?
CMS lists R56.01 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 115 closely related codes in its exclusion list.
Can R56.01 be a principal diagnosis?
Use it with care. This is a symptom code, so once a definitive diagnosis explaining the complex febrile convulsions is established, that condition takes the principal position instead.
What HCC is R56.01?
R56.01 (complex febrile convulsions) maps to CMS-HCC Category 201 (Seizure Disorders and Convulsions), commonly written as HCC 201, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 79 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does R56.01 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, R56.01 adds a risk adjustment factor of about 0.245 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.131 to 0.245 depending on the payment segment). HCC 201 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 201 category page.
