ICD-10-CM Official Guidelines
The Official Guidelines for Coding and Reporting are the authority for assigning ICD-10-CM codes. ICD10Ref does not replace them.
Get the FY2027 Guidelines
- FY 2027 ICD-10-CM Official Guidelines for Coding and Reporting (PDF, CMS)
- ICD-10 on cms.gov: code sets, guidelines and addenda
- ICD-10-CM on cdc.gov (NCHS), the maintainers of the classification
The FY2027 Guidelines are effective October 1, 2026. Following them is required under HIPAA, and where the conventions of the classification and the Guidelines differ, the conventions take precedence.
How the Guidelines are organized
- Section I: conventions, general coding guidelines and chapter-specific guidelines.
- Section II: selection of the principal diagnosis.
- Section III: reporting additional diagnoses.
- Section IV: diagnostic coding and reporting for outpatient services.
Where this site’s explanations come from
The short captions you see on code pages follow these parts of Section I of the FY2027 Guidelines. Read the Guidelines themselves for the full rules.
- I.A.12.aExcludes1: “not coded here.” The excluded code should never be used at the same time, with an exception when the two conditions are unrelated.
- I.A.12.bExcludes2: “not included here.” A patient may have both conditions, and both codes can be used when appropriate.
- I.A.13, I.B.7Code first and Use additional code: the underlying condition is sequenced first, if known, and the secondary code is added, if known.
- I.A.17Code also: two codes may be required, and the note gives no sequencing direction.
- I.A.16See and see also in the Alphabetic Index.
- I.B.1Locating a code: use both the Alphabetic Index and the Tabular List; a dash means more characters are required.
Guidelines tips on code pages
Some code pages show a short tip taken from the Guidelines. Each tip links to the official text it comes from, quoted exactly. A tip is added only when the Guidelines say it. 160 tips so far.
General (31) Infections (11) Neoplasms (8) Endocrine (8) Mental health (6) Nervous system (4) Eye (2) Circulatory (16) Respiratory (5) Skin (3) Musculoskeletal (3) Genitourinary (2) Pregnancy (17) Perinatal (7) Congenital (1) Symptoms (6) Injury (13) External causes (7) Z codes (10)
General conventions and guidelines (Sections I.A and I.B)31 tips
- IConventions take precedence over guidelines
- I.A.3Only codes are reported, with every required character
- I.A.4Placeholder X and the 7th character
- I.A.6NEC and NOS
- I.A.7Brackets and parentheses
- I.A.9"Other" and "unspecified" codes
- I.A.11Inclusion terms are not exhaustive
- I.A.12.aExcludes1 notes
- I.A.12.bExcludes2 notes
- I.A.13Etiology and manifestation: code first and use additional code
- I.A.14The word "and" in a title
- I.A.15The word "with"
- I.A.16"See" and "See also"
- I.A.17"Code also" notes
- I.A.18Default codes
- I.A.19Code assignment and clinical criteria
- I.B.1Locating a code: Index first, then Tabular List
- I.B.2Level of detail in coding
- I.B.5Signs and symptoms that are integral to a disease
- I.B.7Multiple coding for a single condition
- I.B.8Acute and chronic conditions
- I.B.9Combination codes
- I.B.10Sequela (late effects)
- I.B.11Impending or threatened conditions
- I.B.12Reporting the same code more than once
- I.B.13Laterality
- I.B.14Documentation by clinicians other than the provider
- I.B.15Syndromes
- I.B.16Complications of care
- I.B.17Borderline diagnoses
- I.B.18Sign, symptom and unspecified codes
Chapter 1: Infectious and parasitic diseases11 tips
- I.C.1.a.1HIV: confirmed cases and code B20
- I.C.1.bOrganism codes for infections in other chapters
- I.C.1.cResistance to antimicrobial drugs (Z16)
- I.C.1.d.1.aSepsis, severe sepsis and urosepsis
- I.C.1.d.1.aSepsis, unspecified organism, and urosepsis
- I.C.1.d.2Septic shock
- I.C.1.d.5Sepsis due to a postprocedural infection
- I.C.1.d.9Hemolytic-uremic syndrome associated with sepsis
- I.C.1.e.1.aMRSA infections with a combination code
- I.C.1.f.1Zika virus: confirmed cases only
- I.C.1.g.1COVID-19: confirmed cases only
Chapter 2: Neoplasms8 tips
- I.C.2.c.1Anemia with a malignancy or its treatment
- I.C.2.e.2Encounters for chemotherapy, immunotherapy and radiation therapy
- I.C.2.jDisseminated and unspecified malignant neoplasm
- I.C.2.l.2Treatment directed at a secondary site
- I.C.2.l.3Malignant neoplasm in a pregnant patient
- I.C.2.l.6Pathological fracture due to a neoplasm
- I.C.2.mCurrent malignancy versus personal history of malignancy
- I.C.2.nLeukemia and myeloma: remission or history
Chapter 4: Endocrine, nutritional and metabolic diseases8 tips
- I.C.4.aDiabetes: combination codes
- I.C.4.a.1Type 2 diabetes in remission and presymptomatic type 1
- I.C.4.a.2Diabetes mellitus: type not documented and insulin use
- I.C.4.a.3Combinations of long-term diabetes drug use
- I.C.4.a.5Insulin pump malfunction
- I.C.4.a.6Secondary diabetes mellitus
- I.C.4.a.6.b.iDiabetes after pancreatectomy
- I.C.4.b.1Obesity class codes
Chapter 5: Mental and behavioral disorders6 tips
Chapter 6: Nervous system4 tips
- I.C.6.b.1Pain codes in category G89
- I.C.6.b.3Postoperative pain
- I.C.6.b.4Chronic pain versus chronic pain syndrome
- I.C.6.b.5Neoplasm related pain (G89.3)
Chapter 7: Eye and adnexa2 tips
Chapter 9: Circulatory system16 tips
- I.C.9.aHypertension: presumed link to heart and kidney disease
- I.C.9.a.1Hypertension with heart disease
- I.C.9.a.2Hypertensive heart disease and chronic kidney disease
- I.C.9.a.6Secondary hypertension needs two codes
- I.C.9.a.7Transient or elevated blood pressure
- I.C.9.a.10Hypertensive crisis
- I.C.9.a.12Resistant hypertension
- I.C.9.bAtherosclerotic heart disease with angina pectoris
- I.C.9.cIntraoperative and postprocedural stroke
- I.C.9.d.1Hemiplegia and monoplegia: dominant and nondominant side
- I.C.9.d.2Sequelae of cerebrovascular disease (I69)
- I.C.9.e.1Acute myocardial infarction: the four-week time frame
- I.C.9.e.1STEMI and NSTEMI
- I.C.9.e.4Subsequent acute myocardial infarction
- I.C.9.e.5Type 2 and other types of myocardial infarction
- I.C.9.e.6Myocardial infarction with coronary microvascular dysfunction
Chapter 10: Respiratory system5 tips
- I.C.10.a.1COPD and asthma: acute exacerbation
- I.C.10.b.1Acute respiratory failure
- I.C.10.cInfluenza: identified and unidentified viruses
- I.C.10.d.1Ventilator associated pneumonia
- I.C.10.eVaping-related disorders
Chapter 12: Skin and subcutaneous tissue3 tips
- I.C.12.a.1Pressure ulcer stages
- I.C.12.a.2Pressure ulcers: unstageable, healed and progressing
- I.C.12.b.2Non-pressure chronic ulcers
Chapter 13: Musculoskeletal system and connective tissue3 tips
Chapter 14: Genitourinary system2 tips
Chapter 15: Pregnancy, childbirth and the puerperium17 tips
- I.C.15.a.3Pregnancy: the trimester character
- I.C.15.b.1Routine prenatal visits (Z34)
- I.C.15.b.2Supervision of high-risk pregnancy (O09)
- I.C.15.b.5Outcome of delivery (Z37)
- I.C.15.dPre-existing hypertension in pregnancy (O10)
- I.C.15.fHIV in pregnancy, childbirth and the puerperium
- I.C.15.gDiabetes in pregnancy and gestational diabetes
- I.C.15.kPuerperal sepsis (O85)
- I.C.15.lAlcohol, tobacco and drug use in pregnancy
- I.C.15.mPoisoning and adverse effects in a pregnant patient
- I.C.15.nNormal delivery (O80)
- I.C.15.o.5Pregnancy associated cardiomyopathy (O90.3)
- I.C.15.pSequelae of pregnancy complications (O94)
- I.C.15.q.2Retained products of conception after an abortion
- I.C.15.q.4Hemorrhage following elective abortion
- I.C.15.rAbuse in a pregnant patient
- I.C.15.sCOVID-19 in pregnancy, childbirth and the puerperium
Chapter 16: Perinatal conditions7 tips
- I.C.16.a.1Perinatal codes and the maternal record
- I.C.16.a.2Liveborn infant code Z38
- I.C.16.bNewborn observation for suspected conditions not found (Z05)
- I.C.16.dPrematurity and low birth weight (P05, P07)
- I.C.16.fBacterial sepsis of the newborn (P36)
- I.C.16.gStillbirth (P95)
- I.C.16.hCOVID-19 in a newborn
Chapter 17: Congenital malformations and chromosomal abnormalities1 tip
Chapter 18: Symptoms, signs and abnormal findings6 tips
- I.C.18.aSymptom and sign codes
- I.C.18.dRepeated falls and history of falling
- I.C.18.eComa and the Glasgow coma scale
- I.C.18.gSIRS due to a non-infectious process
- I.C.18.hDeath, not otherwise specified (R99)
- I.C.18.iNIH stroke scale scores
Chapter 19: Injury, poisoning and certain other consequences of external causes13 tips
- I.C.19.aInjuries: application of 7th characters
- I.C.19.bCoding of injuries
- I.C.19.bUnspecified multiple injuries (T07)
- I.C.19.cTraumatic fractures: open, closed, displaced and 7th characters
- I.C.19.c.3Physeal fractures
- I.C.19.dBurns: depth, same site, healing and infection
- I.C.19.d.5Burn, body region unspecified (T30)
- I.C.19.d.6Burns by extent of body surface (T31, T32)
- I.C.19.d.7Burn sequelae and external cause
- I.C.19.ePoisoning, adverse effects and the Table of Drugs
- I.C.19.fAbuse, neglect and other maltreatment
- I.C.19.g.3.aTransplant complications (T86)
- I.C.19.g.5Postprocedural complications in the body system chapters
Chapter 20: External causes of morbidity7 tips
- I.C.20.a.2External cause codes
- I.C.20.bPlace of occurrence (Y92)
- I.C.20.cActivity codes (Y93)
- I.C.20.gPerpetrator of maltreatment and neglect (Y07)
- I.C.20.hUnknown or undetermined intent
- I.C.20.jTerrorism
- I.C.20.kExternal cause status (Y99)
Chapter 21: Factors influencing health status (Z codes)10 tips
- I.C.21.c.1Contact and exposure Z codes (Z20, Z77)
- I.C.21.c.2Inoculations and vaccinations (Z23)
- I.C.21.c.3Status Z codes
- I.C.21.c.4Personal and family history Z codes
- I.C.21.c.5Screening Z codes
- I.C.21.c.6Observation Z codes (Z03, Z04)
- I.C.21.c.7Aftercare Z codes
- I.C.21.c.8Follow-up Z codes (Z08, Z09)
- I.C.21.c.9Donors of organs and tissues (Z52)
- I.C.21.c.12Routine and administrative examinations (Z00-Z02)
See also the Terms and Disclaimer.