Medical Billing & Coding Interview Prep

What's the difference between medical billing and medical coding?

Coding translates the provider's documentation — diagnoses and procedures — into standardized codes (ICD-10-CM, CPT, HCPCS). Billing takes those codes, builds the claim, submits it to the payer, and follows up on payment and denials. Many people do both.

What are the three main code sets and what does each do?

ICD-10-CM = diagnoses/conditions (why the patient was seen). CPT = procedures and services the provider performed. HCPCS Level II = supplies, drugs, durable medical equipment, and services not in CPT.

How many characters can an ICD-10-CM code have, and what does the 7th character mean?

3 to 7 characters. The 7th character often shows the encounter type — "A" initial encounter, "D" subsequent, "S" sequela — especially for injuries.

What is the difference between ICD-10-CM and ICD-10-PCS?

CM is for diagnoses in all settings. PCS is for inpatient hospital procedures only.

Walk me through how you'd look up a diagnosis code.

Start in the Alphabetic Index to find the main term, then always verify in the Tabular List for the complete, most specific code, checking all instructional notes (like "code first" or "use additional code"). Never code straight from the Index.

What does "code first" mean?

It's an instruction to sequence the underlying cause/etiology code before the manifestation code.

What are CPT modifiers, and can you give examples?

Two-digit add-ons that give extra detail without changing the base code. Examples: 25 (a significant, separate E/M on the same day as a procedure), 59 (distinct procedural service), 50 (bilateral), 26 (professional component), 51 (multiple procedures), RT/LT (right/left).

What's the difference between modifier 26 and TC?

26 = professional component (the physician's interpretation). TC = technical component (the equipment/facility). Together they make up the global service.

What are the three categories of CPT codes?

Category I (the main 5-digit procedure codes), Category II (performance-measurement tracking codes), and Category III (emerging/experimental services).

What is an add-on code?

A code (marked with a "+") that's reported with a primary procedure and never billed alone.

What is E/M coding?

Evaluation and Management — office visits, consults, hospital visits. Levels are now driven mainly by medical decision-making or total time under the current guidelines.

What do you do when there's no exact CPT code for a procedure?

Use the unlisted procedure code for that section and submit supporting documentation.

What are NCCI edits?

National Correct Coding Initiative edits — CMS rules that prevent improper code pairings and unbundling.

What's the difference between unbundling and a legitimate use of modifier 59?

Unbundling is improperly billing components separately to get paid more — that's non-compliant. Modifier 59 is the correct way to report a genuinely distinct service when documentation supports it.

What's the global surgical package?

The surgery code includes related pre-op, intra-op, and routine post-op care within a set period, so you don't separately bill those routine follow-ups.

What is upcoding, and why does it matter?

Billing a higher level of service than documentation supports. It's fraud — it inflates reimbursement and creates serious legal and compliance risk.

What's the difference between a CPC and a CPC-A?

Same exam and knowledge — the "A" (Apprentice) just means the experience requirement hasn't been documented yet, typically satisfied through a coding practicum and training certificate.

How do you keep your coding accurate?

Code only what's documented, follow the official guidelines, verify in the Tabular List, check NCCI edits and payer rules, and query the provider when documentation is unclear rather than guessing.

Walk me through the revenue cycle.

Patient registration → insurance verification → the encounter and documentation → coding → charge entry → claim submission → payer adjudication → payment posting → denials/appeals → patient billing → collections.

What is a "clean claim"?

A claim with no errors or missing info that the payer can process without sending it back.

What's the difference between the CMS-1500 and the UB-04?

CMS-1500 = professional/physician (outpatient) claims. UB-04 (CMS-1450) = institutional/hospital facility claims.

What is an EOB?

Explanation of Benefits — the statement the payer sends explaining what was paid, denied, or applied to the patient.

What's the difference between denial and rejection?

A rejection never entered processing (a front-end error — fix and resubmit). A denial was processed but not paid — you research the reason and appeal or correct it.

What is HIPAA, and why does it matter to a coder?

The law protecting patients' protected health information (PHI). Coders handle PHI constantly, so they follow minimum-necessary access, secure systems, and strict confidentiality.

What's the difference between fraud and abuse?

Fraud is intentional deception for benefit (e.g., billing for services not provided). Abuse is improper practice that may not be intentional but still causes incorrect payment.

What are the main types of payers?

Commercial/private insurance, Medicare, Medicaid, TRICARE, workers' compensation, and self-pay patients.

What does Medicare Part A vs. Part B cover?

Part A = inpatient hospital. Part B = outpatient/physician services. (Part C = Medicare Advantage; Part D = drugs.)

What is clinical documentation improvement (CDI)?

Working with providers to make documentation complete and specific so coding is accurate and reflects the true severity of care.

What is "medical necessity"?

The payer's requirement that services be reasonable and appropriate for the diagnosis. The diagnosis (ICD-10-CM) has to justify the procedure (CPT).

What would you do if a provider's documentation doesn't support the code you need?

Submit a compliant physician query for clarification — never assume or code something that isn't documented.

What coding software or tools have you used?

Name whatever encoder and manuals you trained on (e.g., Codify, or your certifying body's manuals), and mention you're comfortable learning EHRs like Epic or Cerner — then reference any specific system named in the job posting.

Do you think AI will replace medical coders?

AI assists with routine coding, but trained coders are still needed to review complex records, catch documentation gaps, ensure compliance, and handle audits and denials — it's a tool that makes accurate coders more valuable, not obsolete.

How do you handle a high volume of charts with tight accuracy standards?

A steady, consistent process: work methodically, double-check against guidelines, flag anything unclear instead of rushing it, and track your own accuracy so you keep improving.

You're behind on your daily chart quota but you hit a confusing record. What do you do?

Accuracy comes before speed — a wrong code costs far more than a slow one. Research it properly or query the provider, and communicate with your lead if a deadline is at risk.

How do you stay current as codes change every year?

Annual code-book updates, continuing-education units and webinars, payer bulletins, and a local professional-association chapter.

How do you handle repetitive work?

Focus on genuinely liking detailed, methodical work, setting a steady rhythm, taking short resets, and finding satisfaction in getting things exactly right.

How do you protect patient privacy day to day?

Access only what's needed, never discuss PHI outside of work, keep your screen and workspace secure, and follow every HIPAA and company policy.

Why medical billing and coding? Why are you switching into this field?

Frame it around your real strengths — precision, organization, persistence — plus the field's stability, demand, and remote-friendliness. Mention your training and certification path as proof you're serious about it long-term.

Why should we hire someone without prior experience?

Formal training across all the code sets, a strong record of accuracy and follow-through, and a coding practicum that functions like a year of real coding cases. Coachable, dependable, and ready to grow with the role.

Sample STAR answer — "Tell me about a time you caught a detail others missed":

Situation: While tutoring, I was reviewing a junior student's submitted work. Task: Make sure it was correct before it went to the teacher. Action: I noticed a recurring error everyone had overlooked and walked the student through the right approach. Result: Their score improved and they stopped repeating the mistake. I bring that same eye for detail to reviewing documentation and codes.