2027 ICD-10-CM Diagnosis Code T31.90Burns involving 90% or more of body surface with 0% to 9% third degree burns

ICD-10-CM Codes›S00–T88›T30-T32›T31

ICD-10-CM T31.90
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

T31.90 is a billable ICD-10-CM diagnosis code for burns involving 90% or more of body surface with 0% to 9% third degree burns. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 935. 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 110 closely related codes. Coders also document this condition as burn any degree involving 90 percent OR more of body surface. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Burn and corrosion, initial encounter.

Code Identity

ICD-10-CM Code
T31.90
Billable Status
Yes — Valid for Submission
Code Describes
Burns involving 90% or more of body surface with 0% to 9% third degree burns
Short Description
Burns of 90%/more of body surfc w 0% to 9% third deg burns
Parent Code
T31.9
Burns involving 90% or more of body surface

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT30-T32Burns and corrosions of multiple and unspecified body regions
CategoryT31Burns classified according to extent of body surface involved
This CodeT31.90Burns involving 90% or more of body surface with 0% to 9% third degree burns

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Burn any degree involving 90 percent OR more of body surface

Coding GuidelinesGuidance

The ICD-10-CM makes a distinction between burns and corrosions. The burn codes are for thermal burns, except sunburns, that come from a heat source, such as a fire or hot appliance. The burn codes are also for burns resulting from electricity and radiation. Corrosions are burns due to chemicals. The guidelines are the same for burns and corrosions.

Sequence first the code that reflects the highest degree of burn when more than one burn is present.

  • When the reason for the admission or encounter is for treatment of external multiple burns, sequence first the code that reflects the burn of the highest degree.
  • When a patient has both internal and external burns, the circumstances of admission govern the selection of the principal diagnosis or first-listed diagnosis.
  • When a patient is admitted for burn injuries and other related conditions such as smoke inhalation and/or respiratory failure, the circumstances of admission govern the selection of the principal or first-listed diagnosis.

Assign codes from category T31, Burns classified according to extent of body surface involved, or T32, Corrosions classified according to extent of body surface involved, when the site of the burn is not specified or when there is a need for additional data. It is advisable to use category T31 as additional coding when needed to provide data for evaluating burn mortality, such as that needed by burn units. It is also advisable to use category T31 as an additional code for reporting purposes when there is mention of a third-degree burn involving 20 percent or more of the body surface.

Categories T31 and T32 are based on the classic "rule of nines" in estimating body surface involved: head and neck are assigned nine percent, each arm nine percent, each leg 18 percent, the anterior trunk 18 percent, posterior trunk 18 percent, and genitalia one percent. Providers may change these percentage assignments where necessary to accommodate infants and children who have proportionately larger heads than adults, and patients who have large buttocks, thighs, or abdomen that involve burns.

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027, published by CMS and the National Center for Health Statistics.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to T31.90: its own notes plus those printed at T31, block T20-T32, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Block T20-T32 applies to 2,584 codes
  • burns (thermal) from electrical heating appliances
  • burns (thermal) from electricity
  • burns (thermal) from flame
  • burns (thermal) from friction
  • burns (thermal) from hot air and hot gases
  • burns (thermal) from hot objects
  • burns (thermal) from lightning
  • burns (thermal) from radiation
  • chemical burn [corrosion] (external) (internal)
  • scalds

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.

  • Burns involving 90% or more of body surface NOS

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 T20-T32 applies to 2,584 codes
  • erythema [dermatitis] ab igne (L59.0)
  • radiation-related disorders of the skin and subcutaneous tissue (L55-L59)
  • sunburn (L55.-)
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes

Use Additional Code

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

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • code to identify any retained foreign body, if applicable (Z18.-)

Notes

General instructions on how these codes are used.

From T31 Burns classified according to extent of body surface involved applies to 55 codes
  • This category is to be used as the primary code only when the site of the burn is unspecified. It should be used as a supplementary code with categories T20-T25 when the site is specified.
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
  • The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.

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

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name T31.90, its category, or a range that includes it.

Use Additional Code 1

These codes say to use an additional code from the note, and T31.90 is one of the codes named.

  • Block T20-T25 Burns and corrosions of external body surface, specified by site
    code from category T31 or T32 to identify extent of body surface involved names T31, 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 INJ019
Burn and corrosion, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Burns

A burn is damage to your body's tissues caused by heat, chemicals, electricity, sunlight, or radiation. Scalds from hot liquids and steam, building fires and flammable liquids and gases are the most common causes of burns. Another kind is an inhalation injury, caused by breathing smoke.

Read the full article at MedlinePlus

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

Convert T31.90 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
948.90 90% + bdy brn/3d deg NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About T31.90Overview

Is T31.90 (Burns involving 90% or more of body surface) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report burns involving 90% or more of body surface with 0% to 9% third degree burns on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does T31.90 group to?

When burns involving 90% or more of body surface with 0% to 9% third degree burns is the principal diagnosis on an inpatient stay, it groups to MS-DRG 935 (Non-Extensive Burns), which carries a relative weight of 2.4232. Higher weights mean higher Medicare reimbursement.

Is T31.90 a CC or MCC?

CMS lists T31.90 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 110 closely related codes in its exclusion list.

What is the ICD-9 equivalent of T31.90?

Under the General Equivalence Mappings, burns involving 90% or more of body surface with 0% to 9% third degree burns converts to ICD-9-CM 948.90 (90% + bdy brn/3d deg NOS). The mapping is approximate, so confirm the match fits the documentation.