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T65.93XS vs Z77

T65.93XS (Toxic effect of unspecified substance, assault, sequela) compared with Z77 (Other contact with and (suspected) exposures hazardous to health), from the official CMS tabular data.

Summary

These codes should not be reported together because T65.93XS’s tabular entry lists Z77 under Excludes1.

Official rule
What is different?

The conditions named, billing status and chapter.T65.93XS is “Toxic effect of unspecified substance, assault, sequela”; Z77 is “Other contact with and (suspected) exposures hazardous to health”. Z77 is a non-billable header; T65.93XS is billable. T65.93XS sits in S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88); Z77 in Z00-Z99 — Factors Influencing Health Status and Contact with Health Services (Z00-Z99).

Registry fact

Can these codes be reported together?

No.T65.93XS’s entry carries an Excludes1 note covering Z77: “contact with and (suspected) exposure to toxic substances (Z77.-)”. Both may be reported only when the documentation shows the two conditions are unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes1 relationship?

Yes.T65.93XS’s tabular entry: “contact with and (suspected) exposure to toxic substances (Z77.-)”. The note covers Z77.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes2 relationship?

Yes.Z77’s tabular entry: “toxic effects of substances chiefly nonmedicinal as to source (T51-T65)”. The note covers T65.93XS.

Official ruleGuide: Excludes1 vs Excludes2

Is one more specific?

Not comparable.The codes sit in different categories; specificity is only comparable within one category.

Is one a parent or header code?

One is a header.Z77 is a non-billable header, but T65.93XS is not one of its subdivisions.

Registry fact

Are there sequencing instructions?

None.Neither entry carries a Code First or Use Additional Code note that names the other.

Official rule

Are there other coding relationships?

None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.

MedCoder-derived

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels

Can these codes be reported together?

Conflict

Excludes1 conflict

T65.93XS
Toxic effect of unspecified substance, assault, sequela
↔
Z77
Other contact with and (suspected) exposures hazardous to health

What we found

No — do not report together.T65.93XS carries an Excludes1 note covering Z77: “contact with and (suspected) exposure to toxic substances (Z77.-)”

Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

What to review

Report one of the two. Both may be reported only when the documentation shows the two conditions are unrelated to each other.

Guide: Excludes1 vs Excludes2Check these on a claim

Why it matters

An Excludes1 note means the two conditions cannot occur together, so the pair should not be reported for the same encounter. The sole exception is when the conditions are documented as unrelated to each other.

Source / rule

CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a

Informational

Excludes2 relationship

Z77
Other contact with and (suspected) exposures hazardous to health
↔
T65.93XS
Toxic effect of unspecified substance, assault, sequela

What we found

Yes, when both are documented.Z77 carries an Excludes2 note covering T65.93XS: “toxic effects of substances chiefly nonmedicinal as to source (T51-T65)”

Excludes2 marks distinct conditions — both may be reported when both are documented.

What to review

Report both only when the documentation supports both conditions; otherwise report the one documented.

Guide: Excludes1 vs Excludes2Check these on a claim

Why it matters

An Excludes2 note means the excluded condition is not part of the code above it, but a patient can have both. Report both when both are documented.

Source / rule

CMS ICD-10-CM tabular instructional notes

Official guidance behind these answers

  • Section I.A.12.a — Excludes1 · applies to: Excludes1

    A type 1 Excludes note is a pure excludes note. It means “NOT CODED HERE!” An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition. An exception to the Excludes1 definition is the circumstance when the two conditions are unrelated to each other. If it is not clear whether the two conditions involving an Excludes1 note are related or not, query the provider. For example, code F45.8, Other somatoform disorders, has an Excludes1 note for "sleep related teeth grinding (G47.63)," because "teeth grinding" is an inclusion term under F45.8. Only one of these two codes should be assigned for teeth grinding. However psychogenic dysmenorrhea is also an inclusion term under F45.8, and a patient could have both this condition and sleep related teeth grinding. In this case, the two conditions are clearly unrelated to each other, and so it would be appropriate to report F45.8 and G47.63 together.

    ICD-10-CM Official Guidelines FY2026

  • Section I.A.12.b — Excludes2 · applies to: Excludes2

    A type 2 Excludes note represents “Not included here.” An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.

    ICD-10-CM Official Guidelines FY2026

Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum

Side by side

T65.93XSToxic effect of unspecified substance, assault, sequelaZ77Other contact with and (suspected) exposures hazardous to health
Billing statusBillableNon-billable header

Report instead: Z77.010, Z77.011, Z77.012, Z77.013, Z77.018

ClassificationS00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)Z00-Z99 — Factors Influencing Health Status and Contact with Health Services (Z00-Z99)
DefinitionToxic effect of unspecified substance, assault, sequela is a billable ICD-10-CM diagnosis code (T65.93XS).Other contact with and (suspected) exposures hazardous to health is a non-billable ICD-10-CM category code (Z77).
7th characterThe appropriate 7th character is to be added to each code from category T65—
Includes—
contact with and (suspected) exposures to potential hazards to health
Excludes1
contact with and (suspected) exposure to toxic substances (Z77.-)
—
Excludes2—
contact with and (suspected) exposure to communicable diseases (Z20.-)
exposure to (parental) (environmental) tobacco smoke in the perinatal period (P96.81)
newborn affected by noxious substances transmitted via placenta or breast milk (P04.-)
occupational exposure to risk factors (Z57.-)
retained foreign body (Z18.-)
retained foreign body fully removed (Z87.821)
toxic effects of substances chiefly nonmedicinal as to source (T51-T65)
Use additional code
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)
—
Code also—
any follow-up examination (Z08-Z09)

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on.

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Derived from the official CMS ICD-10-CM tabular data (FY2026). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources