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The questions are practice questions written in our own words for coding roles; they are not reports of what any employer asks. The answers follow Section IV of the International Classification of Diseases (ICD), Tenth Revision, Clinical Modification (CM), Official Guidelines for Coding and Reporting, published through the Centers for Medicare & Medicaid Services (CMS). That section applies to hospital-based outpatient services and provider-based office visits (CMS, FY 2027 guidelines, Section IV).
The guidelines are reissued every year, with each edition applying from October 1, so the edition in force depends on the date of service. This page cites the FY 2027 edition, which applies from October 1, 2026. The diagnosis answers follow Section IV, and the last group of questions follows a CMS booklet on evaluation and management services. Surgical procedure code selection and provider queries are not covered. For the wider picture of how these interviews run, read the healthcare interviews guide.
Basics: terms and lookup
What do the outpatient coding guidelines cover?
Section IV covers coding and reporting diagnoses for hospital-based outpatient services and provider-based office visits. The general conventions and chapter-specific guidelines in the earlier sections also apply to those visits (CMS, FY 2027 guidelines). State the setting first when you answer a coding question, because the setting decides which rules apply.
Why it is asked: it checks that you know inpatient and outpatient rules are separate sets. Read the full explanation: Section IV introduction of the guidelines.
What is the difference between a first-listed diagnosis and a principal diagnosis?
In the outpatient setting the term first-listed diagnosis is used instead of principal diagnosis. The Uniform Hospital Discharge Data Set (UHDDS) definition of principal diagnosis does not apply to hospital-based outpatient services or office visits (CMS, FY 2027 guidelines). Saying "principal diagnosis" for an office visit signals inpatient habits.
Why it is asked: vocabulary is the quickest test of whether you have worked in the outpatient setting. Read the full explanation: Section IV introduction of the guidelines.
How do you choose the first-listed diagnosis?
The first-listed diagnosis is the condition or reason for the visit chiefly responsible for the services provided. Other conditions that coexist at the visit and affect care are listed after it. When the provider has not confirmed a diagnosis, a symptom or sign from the symptom chapter, Chapter 18, can be first-listed (CMS, FY 2027 guidelines).
Why it is asked: it checks that you tie the first code to the reason for the services, not to the most serious condition in the note. Read the full explanation: Section IV.G of the guidelines.
Where do you start when looking up a diagnosis code?
Start in the Alphabetic Index, then verify the code in the Tabular List. The Alphabetic Index is the lookup list of diagnostic terms that points to candidate codes; the Tabular List is the numbered list of codes with their instructions. Section IV.A says never to begin searching initially in the Tabular List, because that leads to coding errors (CMS, FY 2027 guidelines).
Text description of the diagram
- Start in the Alphabetic Index, then verify the code in the Tabular List.
- Never begin searching in the Tabular List, because that leads to coding errors.
Why it is asked: it shows whether you follow the documented method or guess from memory. Read the full explanation: Section IV.A of the guidelines.
Why must a code be taken to its full length?
Codes can have three to seven characters. A three-character code is used only if it is not further subdivided, and a code is invalid if it is not coded to the full number of characters required, including the seventh character where one applies (CMS, FY 2027 guidelines). A code that merely looks right is not enough; check the Tabular List for subdivisions.
Why it is asked: truncated codes are a common, avoidable error, and the answer shows your checking habit. Read the full explanation: Section IV.F of the guidelines.
How specific should a code be?
Code to the highest level of specificity when the medical record documentation supports it (CMS, FY 2027 guidelines, Section IV.F). The words "when supported" matter: you do not add detail the provider did not document. If the note is too vague for a more specific code, that is a documentation gap to raise through your organization's query process, not something to fill in yourself.
Why it is asked: it tests the balance between precision and not assuming. Read the full explanation: Section IV.F of the guidelines.
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Start Free Trial →Uncertain diagnoses and coexisting conditions
The provider wrote "suspected pneumonia" for a patient with cough and fever. What do you code?
You code the symptoms, not pneumonia. The outpatient guidelines say not to code diagnoses documented as probable, suspected, questionable, rule out, compatible with, consistent with or working diagnosis, and instead to code the condition to the highest degree of certainty for that visit, such as symptoms, signs or abnormal test results (CMS, FY 2027 guidelines). This case is illustrative; find the exact symptom codes in the current code set.
Why it is asked: it is the classic outpatient trap, because inpatient rules allow the opposite. Read the full explanation: Section IV.H of the guidelines.
Why do outpatient rules differ from inpatient rules on uncertain diagnoses?
The guidelines for inconclusive diagnoses (probable, suspected, rule out) were developed for inpatient reporting and do not apply to outpatients. Short-term acute, long-term care and psychiatric hospitals follow the inpatient approach, and the guideline itself points out the difference (CMS, FY 2027 guidelines). A good answer names the setting and then the rule.
Why it is asked: it checks that you can explain the reason for a rule, not only recite it. Read the full explanation: Section IV.H of the guidelines.
Do you code only the main complaint?
No. Code all documented conditions that coexist at the time of the visit and that require or affect patient care, treatment or management. Chronic diseases treated on an ongoing basis may be coded and reported as many times as the patient receives treatment and care for them (CMS, FY 2027 guidelines, Sections IV.I and IV.J). The first-listed diagnosis comes first, and the coexisting conditions follow.
Why it is asked: it separates complete coding from copying the chief complaint. Read the full explanation: Sections IV.I and IV.J of the guidelines.
Which past or resolved conditions can you code?
Do not code conditions that were treated previously and no longer exist. History codes in the Z80 to Z87 range may be used as secondary codes when the past condition or family history affects current care or treatment (CMS, FY 2027 guidelines). The test is always whether the condition affects this visit.
Why it is asked: it checks that you can separate an active problem from background history. Read the full explanation: Section IV.J of the guidelines.
Visit types
How do you code an outpatient surgery that was cancelled because of a contraindication?
Code the reason for the surgery as the first-listed diagnosis, even if the surgery was not performed because of a contraindication (CMS, FY 2027 guidelines, Section IV.A.1). The patient still presented for that reason, and the reason is what the encounter was for. Then add a code from category Z53, persons encountering health services for specific procedures and treatment, not carried out, as a secondary code to show why it was not done (Chapter 21 of the same guidelines, Section I.C.21.c.13); confirm the exact subcode in the current Tabular List.
Why it is asked: it tests whether you code the reason for the encounter, not only the work completed. Read the full explanation: Section IV.A.1 of the guidelines.
What if the postoperative diagnosis differs from the preoperative one?
If the postoperative diagnosis is known to be different from the preoperative diagnosis at the time the diagnosis is confirmed, select the postoperative diagnosis for coding, since it is the most definitive (CMS, FY 2027 guidelines, Section IV.N). The rule applies to ambulatory surgery. Read both diagnoses in the operative documentation before you pick.
Why it is asked: it checks that you favor the most definitive documented finding. Read the full explanation: Section IV.N of the guidelines.
How do you sequence a visit that is only a pre-operative evaluation?
Sequence first a code from subcategory Z01.81-, encounter for pre-procedural examinations (for example Z01.810, pre-procedural cardiovascular examination), then the condition that is the reason for the surgery, and also code any findings of the pre-operative evaluation (CMS, FY 2027 guidelines, Section IV.M). The visit exists to clear the patient for a procedure, so the examination code leads and the condition explains why the procedure is planned.
Why it is asked: it tests sequencing for a visit where the service, not the illness, drives the first code. Read the full explanation: Section IV.M of the guidelines.
How do you code a diagnostic test when a physician has interpreted it?
When a physician has interpreted the test and the final report is available at the time of coding, code the confirmed diagnosis. Do not code related signs and symptoms as additional diagnoses. The guideline notes this differs from inpatient practice (CMS, FY 2027 guidelines). So you do not code every abnormal finding once a confirmed diagnosis exists.
Why it is asked: it checks whether you apply the "highest degree of certainty" idea to test results. Read the full explanation: Section IV.K of the guidelines.
What goes first on a therapeutic-only visit, such as chemotherapy?
For a therapeutic-only visit you sequence the reason for the visit first. The guideline calls chemotherapy or radiation therapy "the only exception to this rule": the appropriate Z code for the service is listed first, and the diagnosis or problem for which the service is performed is listed second (CMS, FY 2027 guidelines). Name both the rule and its exception.
Why it is asked: interviewers use exceptions to see whether you know the rule beyond its headline. Read the full explanation: Section IV.L of the guidelines.
What code do you assign for routine lab or radiology testing with no symptoms?
For encounters for routine laboratory or radiology testing in the absence of any signs, symptoms or associated diagnosis, assign Z01.89, Encounter for other specified special examinations (CMS, FY 2027 guidelines, Section IV.K). If the test is ordered because of a sign or symptom, that sign or symptom is coded instead.
Why it is asked: it checks that you can tell routine testing from testing driven by a complaint. Read the full explanation: Section IV.K of the guidelines.
How do you code a general medical exam that finds something abnormal?
Assign the general examination code "with abnormal findings" first, the Z00.0- or Z00.12- code depending on the exam, plus a secondary code for the finding. An abnormal finding means a newly identified condition or a change in severity of a chronic one (CMS, FY 2027 guidelines). A stable, known chronic condition does not count as abnormal here.
Why it is asked: it tests whether you can define "abnormal" precisely, not just apply a label. Read the full explanation: Section IV.P of the guidelines.
Evaluation and management and modifiers
These answers follow the Centers for Medicare & Medicaid Services (CMS) booklet on evaluation and management (E/M) services (CMS, E/M services booklet, May 2026). The booklet is written for Medicare billing, so say that setting when you answer, and check a payer's own rules before you apply them elsewhere.
How is the level of an office or outpatient E/M visit chosen?
The booklet tells practitioners to use the revised Current Procedural Terminology (CPT) office or outpatient E/M guidelines for levels of medical decision making (MDM), and it also describes selecting the visit level using time (CMS, E/M services booklet, May 2026). So the level rests on either the documented decision making or the documented total time on the date of the visit. Say which one the note supports, and do not mix the two.
Why it is asked: E/M level choice is the core of outpatient professional coding, and the answer shows you know it is documentation-driven. Read the full explanation: the E/M services booklet.
When is a prolonged office or outpatient visit reported?
When the visit level is selected using time, prolonged time can be reported with Healthcare Common Procedure Coding System (HCPCS) add-on code G2212. In the booklet's table, CPT code 99215 covers 40 to 54 minutes of total time, and 99215 with one unit of G2212 covers 69 to 83 minutes (CMS, E/M services booklet, May 2026). The time counted is the reportable time spent with the patient on the date of the visit.
Why it is asked: it checks that you tie a time-based code to documented minutes, not to a guess. Read the full explanation: the prolonged services section of the booklet.
What is HCPCS code G2211, and what does modifier 25 change?
HCPCS has two levels: Level I is the CPT code set, and Level II codes, one letter followed by four digits, cover products, supplies and services that CPT does not (CMS, HCPCS overview). G2211 is a Level II, Medicare-specific add-on code for certain complex E/M visits, such as a visit that is the continuing focal point for all needed services.
It cannot be reported without one of its base service codes, and it is not paid when the base code is reported with modifier 25, except for the annual wellness visit, vaccine administration and Medicare Part B preventive services (CMS, E/M services booklet, May 2026). The booklet also uses modifier 25 for a same-day, significant and separately identifiable E/M service on a claim that includes critical care.
Why it is asked: add-on codes and modifiers are where claim edits and denials often start, so interviewers probe them. Read the full explanation: the G2211 section of the booklet.
What must the record show to bill an E/M visit with G2211?
You must document the reason for billing the E/M visit, and the visit must be medically reasonable and necessary. The booklet lists supporting documentation such as information in the medical record or the claim history for the patient and practitioner, the diagnoses, the practitioner's assessment and plan, and the other service codes billed (CMS, E/M services booklet, May 2026).
Why it is asked: it tests whether you link a code to the documentation that supports it. Read the full explanation: the G2211 section of the booklet.
Follow-up questions
What are common outpatient coding interview questions?
They tend to test the points above: first-listed against principal diagnosis, uncertain terms, coexisting conditions, surgery and exam visits, and the lookup method. Practice saying each rule in one sentence, then the exception. For the billing side of the same work, see the medical billing interview questions.
Which guideline year should I study?
Study the edition in force for the dates of service in the role you want, and check which one that is. The guideline text cited here is the FY 2027 edition, effective October 1, 2026 through September 30, 2027. For earlier dates of service, use the edition that applied then.
How should I answer if I do not know a code?
Say how you would find it: search the Alphabetic Index, verify in the Tabular List, and take the code to its full length. Interviewers can accept a clear method more readily than a code recalled wrongly.
Are there question lists for other healthcare roles?
Yes. Clinical and support roles have their own lists, such as nurse interview questions, certified nursing assistant (CNA) interview questions and x-ray technician interview questions.
- Outpatient coding uses the first-listed diagnosis, not the principal diagnosis.
- Do not code "probable", "suspected" or "rule out" in outpatient; code the symptom, sign or finding.
- Start in the Alphabetic Index, verify in the Tabular List, and code to full length.
- Code all coexisting conditions that affect care, but not resolved ones.
- Surgery, test, therapy and exam visits each have their own sequencing rule; learn the exceptions.
- E/M levels rest on documented decision making or documented time, and add-on codes and modifiers need their own documentation.
Sources
- ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (Section IV: outpatient services) — CMS and National Center for Health Statistics, 1 Oct 2026
- Evaluation and Management Services (MLN Booklet, May 2026) — Centers for Medicare & Medicaid Services, 1 May 2026
- Healthcare Common Procedure Coding System (HCPCS) overview — Centers for Medicare & Medicaid Services, 2 Oct 2026
