Your billing company tells you everything is running smoothly. Claims are going out. Payments are coming in. But your revenue feels lower than it should be, your AR keeps climbing, and denials seem to resolve slower every month.
A medical billing audit is how you find out what is actually happening — not what your billing team is telling you is happening.
This guide explains what a medical billing audit is, the seven specific revenue problems it uncovers, the benchmarks to measure your practice against, and a step-by-step process for conducting one — whether your billing is in-house or outsourced.
What Is a Medical Billing Audit?
A medical billing audit is a systematic review of a practice’s billing records, claim submissions, denial patterns, payment postings, and accounts receivable to identify where revenue is being lost, delayed, or left uncollected.
It is different from a compliance audit (which evaluates coding accuracy against clinical documentation for regulatory purposes) and different from a payer audit (which is a government or insurance company review of your claims). A billing performance audit is something you initiate — voluntarily, proactively — to evaluate how well your billing operation is actually functioning.
Practices typically conduct a billing audit in three situations:
- Revenue has declined without a clear clinical explanation
- They are evaluating whether to switch billing vendors or bring billing in-house
- They suspect their current billing team is underperforming but lack the data to confirm it
In each case, the audit produces a clear picture of performance against established industry benchmarks — and identifies specific, fixable problems rather than vague dissatisfaction.
7 Things a Medical Billing Audit Reveals
1. Your Real Denial Rate
According to HFMA (Healthcare Financial Management Association), a denial rate below 5% is optimal. The industry average in 2026 runs between 9% and 12% per MGMA (Medical Group Management Association) data. If your denial rate is above 10%, you have a systematic problem — not just bad luck with payers.
A billing audit breaks down your denial rate by payer, by denial code, and by service type. This matters because a 12% denial rate is not one problem — it is usually three or four specific problems. CO-4 (procedure inconsistent with modifier), CO-97 (paid under a different service), and CO-50 (not medically necessary) each require a different fix. Treating them as one number means fixing none of them.
Aayur’s denial management services are built specifically around this kind of root-cause analysis — identifying the denial codes that account for the most dollar volume, not just the most claim volume.
2. Your Clean Claim Rate on First Submission
A clean claim is one accepted by the payer on first submission without a request for correction or additional information. The industry benchmark is a clean claim rate above 95%. Most practices with in-house billing or with underperforming billing vendors run at 75% to 85% — meaning 15% to 25% of every claim batch requires rework before it can be paid.
Every reworked claim costs time and delays payment. A claim that should be paid in 14 to 21 days instead takes 45 to 60 days by the time it is corrected, resubmitted, and processed. At scale, a 20% rework rate represents a significant, ongoing cash flow drag that a clean submission rate would eliminate.
3. Days in Accounts Receivable
Days in AR measures how long it takes, on average, from the date of service to the date of payment. HFMA’s MAP Keys benchmarks put best-in-class performance at under 35 days, with the acceptable range at 30 to 40 days. Days in AR above 50 indicates a collections process that is not functioning.
High days in AR is often the first symptom practices notice — revenue feels “slow” — but the cause can be any combination of slow claim submission, high denial rates, insufficient payer follow-up, or patient balance collection failures. The audit identifies which of these is driving the number.
4. AR Aging Buckets — Specifically What Is Over 90 Days
An AR aging report segments outstanding balances by how long they have been open: 0–30 days, 31–60 days, 61–90 days, and over 90 days. Industry benchmarks suggest that claims over 90 days should represent less than 25% of your total outstanding AR. Practices that let claims age past 90 days without aggressive follow-up see recovery rates drop significantly — payers become harder to reach, timely filing deadlines approach, and smaller balance claims get deprioritized or abandoned entirely.
A billing audit pulls this aging report and reviews what is actually sitting in the over-90-days bucket: payer-held claims, appealed denials that were never followed up, or patient balances that were never collected. Each category requires a different intervention.
5. Write-Off Patterns
Write-offs are legitimate — contractual adjustments for in-network rates are expected. But billing audits frequently uncover write-offs that should not be write-offs: claims written off as timely filing denials when the filing deadline was missed by the billing team, claims written off as “uncollectible” that were never appealed, and patient balances written off without a statement ever being sent.
Separating legitimate contractual adjustments from avoidable write-offs is a core function of a billing audit. If your write-offs include any of the categories above, that revenue was collectable — and lost due to process failure, not payer behavior. Understanding timely filing limits by payer is essential to preventing one of the most avoidable write-off categories.
6. Coding Accuracy and Upcoding/Downcoding Patterns
A billing audit includes a sample review of coded claims against the corresponding documentation. This surfaces two distinct problems that cut in opposite directions:
- Downcoding — Billing lower-complexity codes than the documentation supports. Common when billing staff are not familiar with the specialty’s documentation requirements. The practice legally earned a higher reimbursement and did not collect it.
- Upcoding — Billing higher-complexity codes than the documentation supports. A compliance risk that can trigger payer audits, recoupment demands, and in serious cases, fraud investigation under the False Claims Act.
Both are problems. An audit catches both — and identifies whether the pattern is systemic (a training gap) or isolated (a specific provider or coder).
7. Net Collection Rate
Net collection rate measures how much of the money the practice was entitled to collect — after contractual adjustments — was actually collected. The target is above 95%. A net collection rate below 90% means 10 cents or more of every legitimate dollar owed to the practice is being left uncollected.
This is the single number that summarizes overall billing performance. A billing team can have a plausible-sounding explanation for every individual problem — slow payers, complex patients, documentation issues — but a net collection rate below 90% is hard to explain away. It is the number that most directly answers whether your billing operation is doing its job.
Medical Billing Benchmarks: What Good Looks Like
| Metric | Best-in-Class Target | Industry Average | Red Flag |
|---|---|---|---|
| Denial rate | <5% | 9–12% | >15% |
| Clean claim rate (first pass) | >95% | 75–85% | <70% |
| Days in AR | <35 days | 40–55 days | >60 days |
| AR over 90 days (% of total AR) | <15% | 25–35% | >40% |
| Net collection rate | >95% | 90–95% | <85% |
Sources: HFMA MAP Keys benchmarks, MGMA cost and revenue survey data. These benchmarks apply to most medical specialties; high-complexity specialties (oncology, transplant, behavioral health) may have higher baseline denial rates due to payer-specific coverage policies.
How to Conduct a Medical Billing Audit
A basic billing performance audit can be conducted in five steps. You do not need to be a billing expert to run one — you need your billing software’s reporting tools and the benchmarks above.
- Pull your denial report for the past 90 days. Sort by denial code and by dollar amount. Identify the top three denial reasons by total dollars denied — not total number of claims. A CO-50 denial on a $12 claim matters less than a CO-97 denial on a $450 claim.
- Run your AR aging report. Calculate what percentage of your total open AR is over 90 days. If it exceeds 25%, segment it further: how much is with payers vs. patients, and how many of the payer-held claims have had a follow-up contact in the past 30 days?
- Calculate your days in AR. The formula is: total AR balance ÷ (total charges for last 90 days ÷ 90). A result above 45 days warrants investigation.
- Review your write-offs. Ask your billing team to provide a write-off report for the last six months categorized by reason: contractual adjustment, timely filing, no authorization, uncollectible patient balance, other. Any significant volume in “timely filing” or “other” indicates avoidable losses.
- Sample your coding. Pull 20 to 30 claims from your highest-volume service codes and compare the level of service billed against the clinical note. If you find consistent mismatches in either direction, that is a training issue requiring immediate attention.
When Should a Practice Audit Its Medical Billing?
At minimum, practices should review their core billing metrics quarterly. A full audit — including coding review, write-off analysis, and payer-level AR breakdown — should be conducted annually or any time:
- Collections decline for two consecutive months without a corresponding drop in patient volume
- A new payer contract is added or renegotiated
- A billing staff member leaves or is replaced
- The practice changes billing software or moves from in-house to outsourced billing (or vice versa)
- A payer issues a request for records or a post-payment review
The worst time to discover a billing problem is when it has been compounding undetected for 12 months. At that point, the timely filing window for older claims may have closed, recovered denials become statistically unlikely, and the write-offs are permanent. Regular audits catch problems while they are still fixable.
Frequently Asked Questions About Medical Billing Audits
What is the difference between a billing audit and a compliance audit?
A billing performance audit evaluates how well the billing process is functioning — claim submission rates, denial rates, AR aging, and collection rates. A compliance audit evaluates whether the services billed are accurately documented and coded in accordance with payer and regulatory requirements. The two overlap when coding accuracy is reviewed, but they serve different purposes. A billing audit is an internal performance review; a compliance audit is a risk management exercise. Both are recommended, but they answer different questions.
Can I audit my billing company’s performance?
Yes, and you should. Your billing company works on your behalf and with your data. You are entitled to request a denial report, AR aging report, write-off report, and clean claim rate report at any time. A billing company that resists providing these reports or provides them only in formats that are difficult to interpret is a billing company that does not want you to know its actual performance numbers. Transparent performance reporting is a baseline expectation, not a favor.
What is a good denial rate for a medical practice?
HFMA considers a denial rate below 5% optimal. Most well-run practices operate between 5% and 8%. The industry average sits at 9% to 12%. If your denial rate exceeds 12%, you have a systematic problem — most likely in eligibility verification, prior authorization, or coding — that a targeted process change can address. See our guide to denial management in medical billing for a breakdown of the most common denial codes and how to resolve each.
How long does a medical billing audit take?
A basic self-audit using your billing software’s existing reports can be completed in a few hours if the reports are accessible. A full audit conducted by an outside RCM team — including coding review, payer-level analysis, and a written findings report — typically takes one to two weeks, depending on the volume of claims reviewed and the complexity of the practice’s payer mix.
What should I do after a billing audit finds problems?
Prioritize by dollar impact, not by ease of fix. Start with the denial codes and AR aging buckets that represent the largest recoverable amounts. For any denial still within the payer’s appeal window, file the appeal immediately. For write-offs that were avoidable (timely filing violations, missed follow-ups), address the process failure that caused them — the individual claims may be unrecoverable, but the same situation should not happen again. If the audit reveals problems your current billing team cannot or will not fix, that is a vendor evaluation conversation, not a billing conversation.
A medical billing audit is the fastest way to move from “something feels off” to “here is exactly what is wrong and what it is costing us.” If you want an outside set of eyes on your billing performance — denial rate, AR aging, net collection rate, and coding accuracy — Aayur Solutions conducts revenue cycle assessments for practices across the country. Our team has over 17 years of RCM experience across medical specialties and knows what your numbers should look like. Contact us to schedule a no-cost assessment.
Written by
Ajay Pillai CEO & Founder, Aayur Solutions LLCAjay Pillai is the CEO of Aayur Solutions LLC, a U.S.-based medical billing and revenue cycle management company serving DME/HME providers, dental practices, pain management clinics, and specialty care organizations. With 17+ years of hands-on RCM experience, he has led billing operations, denial management workflows, and prior authorization programs for healthcare providers across the United States. Ajay holds credentials from the Indian Institute of Management and Case Western Reserve University, and is based in Sheridan, Wyoming.
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