The job and the cycle
What does a medical biller do?
A medical biller prepares and submits claims to insurers, bills patients for their share, posts the payments that come back, and works the claims that are not paid. The U.S. Department of Labor's Occupational Information Network database describes the neighbouring medical records specialist as classifying diagnoses, procedures and services into the healthcare coding system, and lists billing and invoicing software among its software skills (Occupational Information Network, updated 2026).
Why it is asked: it checks that your picture of the job matches the employer's. Read the full explanation: the healthcare interview guide, which covers the wider set of clinical and administrative roles.
What is the difference between medical billing and medical coding?
Coding turns the documentation of a visit into standard codes for the diagnoses and procedures; billing turns those codes into a claim and collects payment. Small practices often combine them. Say which you have done, and that a coding error becomes a billing denial later, so you check the codes against the notes before submitting.
Why it is asked: it tests whether you know where your work starts and ends.
What is the revenue cycle?
The revenue cycle is the path from a patient booking to the final payment, and it runs in order: register the patient, verify coverage, code the visit, submit the claim, post the payment, and follow up on denials and balances. Errors upstream, such as a wrong insurance identifier at registration, surface downstream as denied claims, so strong billers fix causes, not only symptoms.
Why it is asked: it shows whether you think in a process, not in tasks.
Text description of the diagram
- The cycle runs register, verify coverage, code, submit, post and follow up.
- Errors upstream surface downstream as denied claims.
Codes
What are ICD-10, CPT and HCPCS codes?
International Classification of Diseases (ICD) tenth-revision codes, in the Clinical Modification (CM) version called ICD-10-CM, describe diagnoses; the Centers for Medicare & Medicaid Services (CMS) says the Centers for Disease Control and Prevention maintains them (CMS, September 2026). Current Procedural Terminology (CPT) codes describe procedures and services; CPT is a numeric system maintained by the American Medical Association, which CMS calls Healthcare Common Procedure Coding System (HCPCS) Level I. HCPCS Level II codes are used alongside CPT for supplies and services it omits (CMS, October 2026).
Why it is asked: code sets are the vocabulary of the job. Read the full explanation: outpatient coding interview questions.
How often do codes change, and how do you stay current?
ICD-10-CM files (diagnoses) and files for the Procedure Coding System (PCS) part of ICD-10, called ICD-10-PCS (inpatient hospital procedures), are published for each fiscal year; CMS lists new codes effective October 1, 2026, with some mid-year updates (CMS, September 2026). HCPCS Level II updates are released quarterly, effective January, April, July and October (CMS HCPCS, October 2026; quarterly update, September 2026). Stay current by loading updates before they take effect and checking denials that cite an invalid code.
Why it is asked: stale codes cause denials.
How do you check that a code is valid for a date of service?
Use the code set in force on the date of service, not the date you bill. CMS publishes ICD-10 files with the discharge or encounter dates they cover; the 2027 fiscal-year diagnosis files cover October 1, 2026 to September 30, 2027 (CMS ICD-10 page, September 2026). A claim for a visit in September 2026 uses the earlier set, even if it is billed in October.
Why it is asked: it tests attention to dates, a common source of errors.
Knowing it is half the job. Saying it is the other half.
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What is a clean claim, and what rate should you aim for?
A claim is a request for payment sent to a payer (the insurer or government programme that pays the claim); a clean claim is one that passes the payer's checks first time, with no missing or wrong information. If 920 of 1,000 claims are accepted first pass, the clean-claim rate is 92%.1 Targets vary by organisation, so ask what theirs is, and say you reach it by checking eligibility and codes before submitting.
Why it is asked: it is the standard quality measure.
What is the difference between a rejection and a denial?
A rejection means the claim never entered the payer's system, usually because of a format or data error, so you correct it and resubmit. A denial means the payer processed the claim and refused payment, for reasons such as no coverage, no prior authorisation (the payer's advance approval) or a coding mismatch, so you appeal or correct and resubmit within the payer's limits. This is practice; payers use different labels.
Why it is asked: handling differs, and mixing them up loses time.
How do you work a denied claim?
Read the reason on the remittance (the payer's statement of what it paid and why), find the cause in the record, fix what you can and appeal what you cannot, inside the deadline. Track patterns: if the same code or payer keeps denying, fix the source. As an illustration, of 80 denials, if 60% are overturned on appeal that recovers 48, and 32 stay unpaid.1
Why it is asked: denial work is a large part of the role.
What is timely filing?
Timely filing is the deadline by which a claim must reach the payer. For Medicare claims for services on or after January 1, 2010, the claim must be filed no later than the close of the period ending one calendar year after the date of service (Title 42 of the Code of Federal Regulations (CFR), section 424.44); a service on March 15, 2026 gives March 15, 2027, 365 days.1 Private payers set their own limits, so confirm each one.
Why it is asked: a missed deadline usually means unrecoverable revenue.
What do an explanation of benefits and a remittance advice tell you?
They report how the payer processed a claim: what was allowed, what was paid, what the patient owes and the reason codes for any adjustment or denial. The explanation of benefits goes to the patient, and the remittance advice goes to the provider's billing office. You use the remittance to post payments and to find denials.
Why it is asked: reading them is daily work.
What are a deductible, a copayment and coinsurance?
A deductible is the amount a patient pays each year before insurance starts paying. A copayment is a fixed amount for a visit or service. Coinsurance is a percentage of the allowed amount (the price the plan has agreed to pay for a covered service) the patient pays after the deductible; with 20% coinsurance on an illustrative allowed amount of 100 units the patient owes 20. Plans differ, so use the plan's own figures.
Why it is asked: patients ask about these, and you must explain them plainly.
What are days in accounts receivable?
Days in accounts receivable is the outstanding balance divided by the average daily charges, a measure of how fast money is collected. With a balance of 450,000 units and 10,000 units of charges a day, it is 45 days.1 A rising figure suggests slow follow-up or growing denials. Targets vary by organisation and payer mix, meaning the share of revenue from each insurer.
Why it is asked: it is the standard measure of collection speed.
Compliance and judgment
What does HIPAA require of a medical biller?
The Health Insurance Portability and Accountability Act (HIPAA) Privacy Rule bars covered entities (such as providers and health plans) and their business associates (outside firms that handle the data for them) from using or disclosing protected health information, which is health information that identifies, or could identify, a patient, including billing and payment records (45 CFR 160.103), except as permitted. When using, disclosing or requesting it they must make reasonable efforts to limit it to the minimum necessary (45 CFR 164.502). Practise this: open only the records your task needs.
Why it is asked: privacy mistakes are serious and avoidable.
What would you do if a provider asks you to bill a higher-paying code than the notes support?
Decline to bill it and explain why: a code must match the documentation. Offer a compliant route, such as asking the provider to clarify or add the missing documentation if care was actually delivered, and escalate to the compliance officer if pressure continues. Keep a record of the request. Never change a code to raise payment.
Why it is asked: it tests integrity under pressure. Read the full explanation: behavioural answers with the situation, task, action, result method.
How do you handle a patient who disputes a bill?
Listen, then check the claim and the remittance before answering. If the bill is right, explain each line in plain words and offer a payment plan if your policy allows. If it is wrong, correct it and confirm in writing. Stay calm, stay factual and never discuss the account with anyone unauthorised.
Why it is asked: billers meet upset patients every week. Read the full explanation: behavioural healthcare interview questions.
How do you keep accurate when volume is high?
Build checks into the routine: verify coverage before submitting, use payer edits (the payer's automatic checks) or a scrubber (software that checks a claim before it goes out) to catch errors, work the oldest and largest balances first, and keep a short log of repeat errors with fixes. Accuracy beats speed because a rejected or denied claim costs more time than the minute saved.
Why it is asked: volume tests habits.
Tools and fit
Which billing software have you used?
Name the systems, the tasks you did in each and the volume, for example posting payments, working a denial queue or running aging reports (lists of unpaid claims by age). The Occupational Information Network page for the neighbouring medical records specialist occupation lists billing and invoicing software among its software skills (Occupational Information Network, updated 2026). If you have not used their system, say how you learned similar ones.
Why it is asked: it separates experience from familiarity.
Why do you want to work in medical billing?
Tie your reason to the work: accuracy, the satisfaction of fixing a claim, and keeping care financially sustainable for the provider. Give one example of a problem you solved. Avoid saying it is easy or remote. Practise it with the tell me about yourself structure and an example in the situation, task, action, result (STAR) form.
Why it is asked: it reveals motivation and fit. For a neighbouring healthcare role, see nurse interview questions.
What questions should you ask the interviewer?
Ask what the clean-claim and denial rates are, which payers dominate, which software the team uses, how denials are tracked and who handles appeals. These show you think about outcomes. See questions to ask the interviewer for more.
Why it is asked: it shows how you think about the work.
- Know the cycle: register, verify, code, submit, post, follow up; upstream errors become denials.
- Know the code sets: ICD-10-CM for diagnoses, CPT for procedures, HCPCS Level II for supplies and other services.
- A claim has a filing deadline; for Medicare it is one calendar year after the date of service.
- Bill only what the documentation supports, and use only the minimum necessary patient information.
Sources
- 29-2072.00 Medical Records Specialists, O*NET OnLine summary — National Center for O*NET Development, U.S. Department of Labor (page shows year only, Updated 2026; read 2026-10-26), 26 Oct 2026
- ICD-10 codes — Centers for Medicare & Medicaid Services, 8 Sep 2026
- Healthcare Common Procedure Coding System (HCPCS) — Centers for Medicare & Medicaid Services, 2 Oct 2026
- HCPCS Quarterly Update — Centers for Medicare & Medicaid Services, 23 Sep 2026
- 42 CFR 424.44 Time limits for filing claims — Legal Information Institute, Cornell Law School (page shows no date; read 2026-10-24), 24 Oct 2026
- 45 CFR 160.103 Definitions — Legal Information Institute, Cornell Law School (page shows no date; read 2026-10-26), 26 Oct 2026
- 45 CFR 164.502 Uses and disclosures of protected health information: general rules — Legal Information Institute, Cornell Law School (page shows no date; read 2026-10-24), 24 Oct 2026
