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A05 vs T78.120

A05 (Other bacterial foodborne intoxications, not elsewhere classified) compared with T78.120 (Other adverse food reaction due to egg with tolerance to baked egg), from the official CMS tabular data.

Summary

These codes should not be reported together because T78.120’s tabular entry lists A05 under Excludes1.

Official rule
What is different?

The conditions named and chapter.A05 is “Other bacterial foodborne intoxications, not elsewhere classified”; T78.120 is “Other adverse food reaction due to egg with tolerance to baked egg”. A05 sits in A00-B99 — Certain Infectious and Parasitic Diseases (A00-B99); T78.120 in S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88).

Registry fact

Can these codes be reported together?

No.T78.120’s entry carries an Excludes1 note covering A05: “bacterial food borne intoxications (A05.-)”. 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.T78.120’s tabular entry: “bacterial food borne intoxications (A05.-)”. The note covers A05.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes2 relationship?

None.Neither entry carries an Excludes2 note that names the other code. T78.120 carries 7 Excludes2 notes covering other codes; the side-by-side table quotes them.

Official rule

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?

Both are headers.Both are non-billable headers, and neither contains the other.

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

T78.120
Other adverse food reaction due to egg with tolerance to baked egg
↔
A05
Other bacterial foodborne intoxications, not elsewhere classified

What we found

No — do not report together.T78.120 carries an Excludes1 note covering A05: “bacterial food borne intoxications (A05.-)”

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

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

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

A05Other bacterial foodborne intoxications, not elsewhere classifiedT78.120Other adverse food reaction due to egg with tolerance to baked egg
Billing statusNon-billable header

Report instead: A05.0, A05.1, A05.2, A05.3, A05.4

Non-billable header

Report instead: T78.120A, T78.120D, T78.120S

ClassificationA00-B99 — Certain Infectious and Parasitic Diseases (A00-B99)S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)
DefinitionOther bacterial foodborne intoxications, not elsewhere classified is a non-billable ICD-10-CM category code (A05).Other adverse food reaction due to egg with tolerance to baked egg is a non-billable ICD-10-CM category code (T78.120).
7th character—The appropriate 7th character is to be added to each code from category T78
Excludes1
Clostridium difficile foodborne intoxication and infection (A04.7-)
Escherichia coli infection (A04.0-A04.4)
listeriosis (A32.-)
salmonella foodborne intoxication and infection (A02.-)
toxic effect of noxious foodstuffs (T61-T62)
Other adverse food reaction due to egg with reactivity to baked egg (T78.121)
anaphylactic reaction or shock due to adverse food reaction (T78.0-)
anaphylactic reaction due to food (T78.0-)
bacterial food borne intoxications (A05.-)
Excludes2—
allergic and dietetic gastroenteritis and colitis (K52.29)
allergic rhinitis due to food (J30.5)
dermatitis due to food in contact with skin (L23.6, L24.6, L25.4)
dermatitis due to ingested food (L27.2)
food protein-induced enterocolitis syndrome (K52.21)
food protein-induced enteropathy (K52.22)
complications of surgical and medical care NEC (T80-T88)
Use additional code—
code to identify the type of reaction, if applicable
Code also—
, if applicable, place of occurrence, such as:
highway rest stop (Y92.523)
school (private) (public) (state) as the place of occurrence of the external cause (Y92.21-)
service areas as the place of occurrence of the external cause (Y92.52-)
single-family non-institutional (private) house as the place of occurrence of the external cause (Y92.01-)
transport vehicle as the place of occurrence of the external cause (Y92.81-)

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 (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources