Medical Auditing
Medical auditing tests your ability to plan an audit, select a valid sample, apply current coding and payer rules, calculate error rates, and turn findings into corrective action. The exam expects practical judgment about internal and external audits, RAC and payer reviews, and statistical extrapolation.
Core rules and concepts
- Define the audit objective and scope first: payer, date range, provider, service line, number of claims, and whether the audit is baseline, focused, or follow-up.
- Use the rules in effect on the date of service. Do not apply current-year E/M guidelines to prior-year claims. Validate code selection against CPT, ICD-10-CM/PCS, HCPCS, NCCI edits, and the applicable LCD or payer policy.
- Sampling must fit the objective. A random sample supports an error-rate estimate; a targeted sample supports education but does not support extrapolation. Document the sampling method and sample size rationale.
- Calculate the error rate as claims with at least one error divided by claims reviewed. Calculate financial impact separately; not every documentation error is a payment error.
- Maintain auditor independence, work papers, and a clear report with findings, root cause, corrective action plan, and re-audit date.
Worked example
A compliance officer audits 120 professional claims for a cardiology group. Nine claims have coding errors, but only six changed payment, totaling $2,340. The error rate is 9/120, or 7.5%. The financial error rate is 6/120, or 5%. Because the sample was randomly selected from a defined population and the audit used valid statistical methods, the practice may consider extrapolation; because the dollar amount is small, leadership instead repays the identified overpayment and performs a focused re-audit in 90 days. Using 9/120 to extrapolate dollars would overstate the overpayment because three errors were documentation-only.
Traps that cost marks
- Extrapolating from a convenience or targeted sample.
- Counting every missing signature as a paid claim error without confirming payer policy.
- Auditing only high-level claims and calling the result a population error rate.
- Failing to verify NCCI edits and modifier support.
- Issuing a report with no root cause, owner, or re-audit date.