Medical Billing Audit Checklist: Internal RCM Review

Key Performance Metrics and Benchmarks

Every billing audit starts with measuring your current performance against established benchmarks. If you do not know your numbers, you cannot identify what needs fixing. Pull these metrics for the most recent 90-day period:

Coding Accuracy Audit

The coding accuracy audit is the highest-stakes component — it has both revenue implications and compliance risk. Pull a random sample of 30–50 claims from your top-volume CPT codes and review each one against the clinical documentation.

For each sampled claim, check:

• CPT code accuracy — does the billed code match the documented service? Review for both upcoding (billing a higher level than documented) and downcoding (billing a lower level, which is revenue leakage)
• E&M level selection — for office visits, verify the MDM (Medical Decision Making) or time-based documentation supports the billed level
• ICD-10 diagnosis codes — are all relevant diagnoses captured? Is the primary diagnosis the chief complaint, not an unrelated chronic condition? Do diagnosis codes support medical necessity for the billed procedures?
• Modifier accuracy — are modifiers applied where required (bilateral procedures, multiple procedures, co-surgery, assistant surgeon)? Are unbundling modifiers (59/XU/XS/XE/XP) used appropriately and with documentation support?
• Provider NPI — does the billing NPI match the rendering provider on the claim? Incident-to billing requires specific supervision conditions — verify they are met

A coding accuracy rate below 95% is a significant finding. For specialties with high OIG scrutiny — pain management, behavioral health, orthopedics, home health — engage a certified medical coding auditor annually. Review the OIG Work Plan each year to see whether your specialty's billing patterns are under active federal scrutiny; it publishes the OIG's current audit targets by provider type and service category.

Denial Root Cause Audit

Pull all denials from the audit period and categorize each by root cause — not just the payer's reason code, but the actual internal process failure that caused the denial. Most billing systems report denial reason codes (CARC/RARC), but the cause category requires human review.

Denial root cause categories:

• Front-end failures (target: under 40% of total denials) — eligibility errors, expired or missing prior authorizations, incorrect patient demographics, wrong insurance information
• Coding errors (target: under 20% of total denials) — incorrect CPT, ICD-10, or modifier application; bundling violations; missing codes
• Documentation deficiencies (target: under 15% of total denials) — medical necessity not supported, missing clinical notes, unsigned orders
• Administrative errors (target: under 10% of total denials) — timely filing missed, duplicate claims submitted, wrong payer billed
• Payer-side errors — correct claims denied incorrectly by the payer; these should be appealed immediately

Once you know where denials are coming from, fix the upstream process. A high proportion of front-end denials means your eligibility verification or prior authorization process is broken. A high proportion of coding denials means your coders need training or your scrubber is misconfigured.

Accounts Receivable Aging Audit

The AR aging report shows how long your outstanding claims have been unpaid. Healthy AR is concentrated in the 0–30 day bucket. As claims age beyond 90 days, the probability of collection drops steeply — and beyond 120 days, many claims are approaching timely filing limits for appeals.

For the AR audit, review:

• AR aging by payer — which payers have the most aged AR? Slow-paying payers or payers with high denial rates will show up here
• Top 20 oldest open claims — review each individually. What is blocking resolution? Is there a pending appeal? Has timely filing been missed? Is the account in collections?
• Claims over 120 days with no action — these are at high risk of write-off. Assign them to a collector immediately with a documented resolution plan
• Credit balances — overpayments from patients or payers that have not been refunded. These are a compliance risk and should be refunded promptly

Calculate your AR days using the formula: (Total AR ÷ Average Daily Charges). If your AR days exceed 40, you have a collections problem that requires process changes, not just additional follow-up calls.

Documentation Compliance Review

Documentation is the foundation of compliant billing. Every service billed must be documented — not only in terms of what was done, but why it was medically necessary. Documentation failures create both revenue risk (denials, post-payment audits) and compliance risk (fraud and abuse exposure).

Documentation review checklist:

• Are clinical notes signed and dated by the rendering provider (not just co-signed)?
• Are dates of service on clinical notes consistent with claim dates?
• Does documentation support the billed E&M level based on MDM or time?
• For procedures: is there a procedure note that documents technique, findings, and any complications?
• For orders (imaging, labs, DME): is there a signed order on file for every ordered service?
• For incident-to services: is the supervising physician physically present in the office suite?
• Are addendums and late entries clearly labeled with the addendum date, not the original DOS?
• Are clinical notes free of cloned/copy-paste content that could indicate fraudulent documentation? (Note: CMS and the OIG have specifically flagged copy-paste documentation in EHR systems as an audit risk — OIG EHR copy-paste report)

Payer Compliance and Contract Audit

Each payer has billing requirements that go beyond standard CMS guidelines. Failure to follow payer-specific rules is a common and overlooked denial cause. For each of your top 5 payers, verify:

• Your contracted rates are being paid correctly (compare contracted fee schedule against actual EOB payments)
• Timely filing limits — are you submitting within the payer's window for initial claims and appeals?
• Prior authorization requirements — are all services requiring PA being authorized before delivery?
• Referral requirements — do any services require a formal referral from a PCP?
• Place of service codes — is the correct POS code being used for telehealth vs. office vs. facility services?
• National Correct Coding Initiative (NCCI) edits — are any code pairs being billed together that are subject to bundling rules?

Complete Billing Audit Checklist

Use this checklist for your quarterly internal billing audit. For each item, note the current status (pass/fail/N/A), the responsible party, and any corrective action required.

Claims Submission

• ☐ Clean claim rate ≥ 95% for the audit period
• ☐ Average days to submit from date of service ≤ 3 business days
• ☐ No claims submitted past 50% of the payer's timely filing limit
• ☐ Claim scrubber rules current and active for top payers

Coding and Documentation

• ☐ Random sample of 30+ claims reviewed; coding accuracy ≥ 95%
• ☐ E&M level distribution reviewed for outliers (unusually high 99215 rate)
• ☐ Modifier use reviewed for appropriateness and documentation support
• ☐ ICD-10 codes reviewed for specificity and medical necessity support
• ☐ Signed clinical notes on file for all sampled claims

Denials and Appeals

• ☐ Denial rate ≤ 8% for the audit period
• ☐ All denials worked within 15 business days of receipt
• ☐ Appeal rate on worked denials ≥ 60%
• ☐ Denial root cause analysis completed; corrective actions assigned

Accounts Receivable

• ☐ Days in AR ≤ 40 days
• ☐ AR over 90 days ≤ 25% of total AR
• ☐ All accounts over 120 days reviewed; resolution plan documented
• ☐ Credit balances identified and refund process initiated

Payer Compliance

• ☐ Top 5 payer fee schedules verified against actual payments (compare contracted rates against ERAs)
• ☐ Prior authorization list current for top payers — payers update PA requirements quarterly
• ☐ Provider enrollment and credentialing expiration dates reviewed (Medicare re-validation every 5 years; Medicaid varies by state)
• ☐ No Surprises Act notices posted (physical location + public website)
• ☐ NCCI (National Correct Coding Initiative) edits reviewed for your top CPT code pairs — CMS updates the edit tables quarterly

Patient Collections

• ☐ Patient balance statements sent within 30 days of payer adjudication
• ☐ Point-of-service collection for copays/deductibles ≥ 80% collected at visit
• ☐ Patient collection rate tracked and trending (target ≥ 95% of patient responsibility)