Alphabetic Index FY2027

T63.321A

Toxic effect of venom of tarantula, accidental (unintentional), initial encounter

FY2027Chapter 19: Injury, poisoning and certain other consequences of external causes/T51–T65 Toxic effects of substances chiefly nonmedicinal as to source

BillableComplete code, valid to report
Care settingsHome Health Primary · MMTA - OtherIPF Primary · MS-DRG 917–918IPF Comorbidity · Poisoning

T63.321A (also written T63321A) is a billable ICD-10-CM diagnosis code for toxic effect of venom of tarantula, accidental (unintentional), initial encounter. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 456 codes in category T63 (Toxic effect of contact with venomous animals and plants). Its 7th character, A, means initial encounter. Its coding notes include a Use additional code instruction, 1 Excludes1 entry and 3 Excludes2 entries.

7th character

Category T63 requires a 7th character.

Assembled code T63.321A Open code

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

T36-T65 codes already include the substance and the intent, so no additional external cause code is required. Do not code directly from the Table of Drugs and Chemicals.

Guidelines I.C.19.ePoisoning, adverse effects and the Table of DrugsRead the official text

Use additional code

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

Also from chapter/block level (5 notes)
Inherited from T51–T65 Toxic effects of substances chiefly nonmedicinal as to source
  • code(s):
    • for all associated manifestations of toxic effect, such as: respiratory conditions due to external agents (J60-J70)
    • personal history of foreign body fully removed (Z87.821)
    • to identify any retained foreign body, if applicable (Z18.-)
Inherited from Chapter 19 Injury, poisoning and certain other consequences of external causes
  • code to identify any retained foreign body, if applicable (Z18.-)

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Also from chapter/block level (1 note)
Inherited from T51–T65 Toxic effects of substances chiefly nonmedicinal as to source
  • contact with and (suspected) exposure to toxic substances (Z77.-)

Excludes2

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

Inherited from T63 Toxic effect of contact with venomous animals and plants
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.

Home Health Primary

Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Other clinical group.

Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026

IPF Primary

IPF MS-DRG adjustment. A principal diagnosis of this code groups to one of these MS-DRGs. Which one depends on other facts of the stay, so the factor is a range:

MS-DRGDescriptionFactor
917Poisoning and toxic effects of drugs w MCC1.19
918Poisoning and toxic effects of drugs w/out MCC1.12
A principal diagnosis that groups to none of the 19 designated MS-DRGs gets no MS-DRG adjustment. Otherwise the claim still receives the federal per diem base rate and the other adjustments.

Source: CMS IPF PPS FY 2027 final rule (CMS-1847-F), Addendum A; code lists from the CMS MS-DRG Definitions Manual v44; effective for discharges on or after October 1, 2026

IPF Comorbidity

On the CMS IPF comorbidity list.

Comorbidity categoryFactor
Poisoning1.16
It counts as a comorbidity when reported as a secondary diagnosis and actively treated during the stay. An IPF receives only one adjustment within a category and can receive adjustments in more than one category.

Source: CMS IPF PPS FY 2027 final rule (CMS-1847-F), Addendum B-3 (comorbidity codes with adjustment factor); effective for discharges on or after October 1, 2026

Includes

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

Inherited from T63 Toxic effect of contact with venomous animals and plants
  • bite or touch of venomous animal
  • pricked or stuck by thorn or leaf

Notes

Also from chapter/block level (3 notes)
Inherited from T51–T65 Toxic effects of substances chiefly nonmedicinal as to source
  • When no intent is indicated code to accidental. Undetermined intent is only for use when there is specific documentation in the record that the intent of the toxic effect cannot be determined.
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.