Alphabetic Index FY2027

T30.4

Corrosion of unspecified body region, unspecified degree

FY2027Chapter 19: Injury, poisoning and certain other consequences of external causes/T30–T32 Burns and corrosions of multiple and unspecified body regions

BillableComplete code, valid to report
Care settingsIRF 60% Rule

T30.4 (also written T304) is a billable ICD-10-CM diagnosis code for corrosion of unspecified body region, unspecified degree. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 2 codes in category T30 (Burn and corrosion, body region unspecified). The Alphabetic Index lists it under 1 entry. Its coding notes include a Use additional code instruction and 2 Excludes2 entries.

Guidelines tips

From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.

The 7th character depends on whether the patient is in active treatment, not on who sees the patient. An aftercare Z code is not used for injury aftercare.

Guidelines I.C.19.aInjuries: application of 7th charactersRead the official text

T30 is described as extremely vague and should rarely be used. Burns of multiple sites are for records that do not specify the sites.

Guidelines I.C.19.d.5Burn, body region unspecified (T30)Read the official text

Use additional code

Add the listed code as a secondary code, if known.

Also from chapter/block level (1 note)
Inherited from Chapter 19 Injury, poisoning and certain other consequences of external causes
  • code to identify any retained foreign body, if applicable (Z18.-)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Also from chapter/block level (2 notes)
Inherited from Chapter 19 Injury, poisoning and certain other consequences of external causes
  • birth trauma (P10-P15)
  • obstetric trauma (O70-O71)

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

IRF 60% Rule

On the CMS list of diagnoses used to determine presumptive compliance with the IRF 60 percent rule.

Source: CMS IRF Presumptive Compliance-3, FY 2027 IRF PPS final rule files, effective for discharges on or after October 1, 2026

Inclusion terms

Conditions classified to this code.

This code
  • This code is not for inpatient use. Code to specified site and degree of corrosion
  • Corrosion NOS
  • Multiple corrosion NOS

Notes

Also from chapter/block level (2 notes)
Inherited from Chapter 19 Injury, poisoning and certain other consequences of external causes
  • 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.

Alphabetic Index terms

Terms the official Alphabetic Index lists for this code. 1 entry