02/06/2026
10 Steps to Correct Coding
Follow the 10 steps below to correctly code encounters for health care services.
Step 1: Identify the reason for the visit or encounter (i.e., a sign, symptom, diagnosis and/or condition). The medical record documentation should accurately reflect the patient’s condition, using terminology that includes specific diagnoses and symptoms or clearly states the reasons for the encounter. Choosing the main term that best describes the reason chiefly responsible for the service provided is the most important step in coding. If symptoms are present and documented but a definitive diagnosis has not yet been determined, code the symptoms. For outpatient cases, do not code conditions that are referred to as “rule out,” “suspected,” “probable,” or “questionable.” Diagnoses often are not established at the time of the initial encounter/visit and may require two or more visits to be established. Code only what is documented in the available outpatient records and only to the highest degree of certainty known at the time of the patient’s visit. For inpatient medical records, uncertain diagnoses may be reported if documented at the time of discharge.
Step 2: After selecting the reason for the encounter, consult the alphabetic index. The most critical rule is to begin code selection in the alphabetic index. Never turn first to the tabular list. The index provides cross-references, essential and nonessential modifiers, and other instructional notations that may not be found in the tabular list.
Step 3: Locate the main term entry. The alphabetic index lists conditions, which may be expressed as nouns or eponyms, with critical use of adjectives. Some conditions known by several names have multiple main entries. Reasons for encounters may be located under general terms such as admission, encounter, and examination. Other general terms such as history, status (post), or presence (of ) can be used to locate other factors influencing health.
Step 4: Scan subterm entries. Scan the subterm entries, as appropriate, being sure to review continued lines and additional subterms that may appear in the next column or on the next page. Shaded vertical guidelines in the index indicate the indentation level for each subterm in relation to the main terms.
Step 5: Pay close attention to index instructions. • Parentheses ( ) enclose nonessential modifiers, terms that are supplementary words or explanatory information that may or may not appear in the diagnostic statement and do not affect code selection. • Brackets [ ] enclose manifestation codes that can be used only as secondary codes to the underlying condition code immediately preceding it. If used, manifestation codes must be reported with the appropriate etiology codes. • Default codes are listed next to the main term and represent the condition most commonly associated with the main term or the unspecified code for the main term. • “See” cross-references, identified by italicized type and “code by” cross-references indicate that another term must be referenced to locate the correct code. • “See also” cross-references, identified by italicized type, provide alternative terms that may be useful to look up but are not mandatory. • “Omit code” cross-references identify instances when a code is not applicable depending on the condition being coded. • “With” subterms are listed out of alphabetic order and identify a presumed causal relationship between the two conditions they link. • “Due to” subterms identify a relationship between the two conditions they link. • “NEC,” abbreviation for “not elsewhere classified,” follows some main terms or subterms and indicates that there is no specific code for the condition even though the medical documentation may be very specific. • “NOS,” abbreviation for “not otherwise specified,” follows some main terms or subterms and is the equivalent of unspecified; NOS signifies that the information in the medical record is insufficient for assigning a more specific code. • Following references help coders locate alphanumeric codes that are out of sequence in the tabular section. • Check-additional-character symbols flag codes that require additional characters to make the code valid; the characters available to complete the code should be verified in the tabular section.
Step 6: Choose a potential code and locate it in the tabular list. To prevent coding errors, always use both the alphabetic index (to identify a code) and the tabular list (to verify a code), as the index does not include the important instructional notes found in the tabular list. An added benefit of using the tabular list, which groups like things together, is that while looking at one code in the list, a coder might see a more specific one that would have been missed had the coder relied solely on the alphabetic index. Additionally, many of the codes require a fourth, fifth, sixth, or seventh character to be valid, and many of these characters can be found only in the tabular list.
Step 7: Read all instructional material in the tabular section. The coder must follow any Includes, Excludes 1 and Excludes 2 notes, and other instructional notes, such as “Code first” and “Use additional code,” listed in the tabular list for the chapter, category, subcategory, and subclassification levels of code selection that direct the coder to use a different or additional code. Any codes in the tabular range A00.0–T88.9, Z00–Z99.8, and U00–U85 may be used to identify the diagnostic reason for the encounter. The tabular list encompasses many codes describing disease and injury classifications (e.g., infectious and parasitic diseases, neoplasms, symptoms, nervous and circulatory system, etc.). Codes that describe symptoms and signs, as opposed to definitive diagnoses, should be reported when an established diagnosis has not been made (confirmed) by the physician. Chapter 18 of the ICD-10-CM code book, “Symptoms, Signs, and Abnormal Clinical and Laboratory Findings, Not Elsewhere Classified” (codes R00–R99), contains many, but not all, codes for symptoms. ICD-10-CM classifies encounters with health care providers for circumstances other than a disease or injury in chapter 21, “Factors Influencing Health Status and Contact with Health Services” (codes Z00–Z99). Circumstances other than a disease or injury often are recorded as chiefly responsible for the encounter. A code is invalid if it does not include the full number of characters (greatest level of specificity) required. Codes in ICD-10-CM can contain from three to seven alphanumeric characters. A three-character code is to be used only if the category is not further subdivided into four-, five-, six-, or seven-character codes. Placeholder character X is used as part of an alphanumeric code to allow for future expansion and as a placeholder for empty characters in a code that requires a seventh character but has no fourth, fifth, or sixth character. Note that certain categories require seventh characters that apply to all codes in that category. Always check the category level for applicable seventh characters for that category. ICD-10-CM 2026 10 Steps to Correct Coding ICD-10-CM 2026 xv 10 Steps to Correct Coding
Step 8: Consult the official ICD-10-CM conventions and guidelines. The ICD-10-CM Official Guidelines for Coding and Reporting govern the use of certain codes. These guidelines provide both general and chapter-specific coding guidance.
Step 9: Confirm and assign the code. Having reviewed all relevant information concerning the possible code choices, assign the code that most completely describes the condition. Repeat steps 1 through 9 for all additional documented conditions that meet the following criteria: • They exist at the time of the visit AND • They require or affect patient care, treatment, or management.
Step 10: Sequence codes correctly.
Sequencing is the order in which the codes are listed on the claim. List first the ICD-10-CM code for the diagnosis, condition, problem, or other reason for the encounter/visit that is shown in the medical record to be chiefly responsible for the services provided. List additional codes that describe any coexisting conditions. Follow the official coding guidelines (see the guidelines, section II, “Selection of Principal Diagnosis”; section III, “Reporting Additional Diagnoses”; and section IV, “Diagnostic Coding
