Medical Billing Audit Services

Medical Billing and Coding Audit Services That Will Identify Errors, Underpayments, and Compliance Risks Before Your Payer Does

A2Z’s Medical Billing Audit Services review your claims compared to your medical records and your payer’s regulations; they then explain what is incorrect, how much it will cost to fix, and why you continue to experience this problem. Overcoding is a repayment risk, and undercoding, missed charges, and unworked underpayments quietly cost you money that nobody sees without a review. Our medical billing and coding audit services are built for practices that have never had an outside audit, practices that changed billers or EHRs, and practices that just got a records request from a payer.

What a Medical Billing Audit Covers, and What It Does Not

A medical billing audit checks a sample of your claims against the medical record, the codes billed, and the payment received. It finds how often claims are wrong and, more useful, why they are wrong.

The purpose of a Coding Audit is to verify the accuracy of the coding used in the claims process. The auditor will review the CPT, HCPCS, ICD-10-CM, and Modifiers used for each claim against the documentation provided. In addition to reviewing these codes, a Billing Audit also reviews the charge amount, the claim data (i.e., date of service, etc.), the payment received, and how the claim was handled after it was paid.

What an audit does not accomplish is correct the claims. It doesn’t resubmit those claims, dispute the denials, or collect on the outstanding balances. These are distinct services provided by medical coders, denial managers, and AR collection and recovery professionals.

Types of Medical Billing Audits

The right audit depends on the question you are asking.

A prospective billing audit, also called a pre-bill audit, reviews all submitted claims before sending them to the payer. This allows for correcting any errors prior to being charged. This would make sense for a new provider, new payer, new EHR, or a coding group that has had many issues in the past. On the other hand, a retrospective billing audit (post-payment audit) reviews claims that have already been paid. This type of audit can help identify patterns of errors, underpayments, and potential repayment liability.

An internal billing audit process will be done internally with your own employees. This type of audit can be completed quickly and regularly; however, the employee reviewing the process might not have enough distance from the work to identify errors. An external audit of the billing process will be conducted by an outside party, giving you an objective evaluation and report on their findings.

Focused audits look at one provider, one payer, one code family, or one denial reason. A revenue cycle audit looks across the whole claim lifecycle and gives you a baseline.

How We Run a Medical Billing Audit

A claim audit at A2Z follows the same order every time: agree what is being audited, pull the records, check each claim against the note, group the results by cause, and report back.

01

Agree the scope and the sample.

We settle with you which providers, payers, and dates are covered, and how claims will be picked.

02

Pull the records

We request only the records the audit needs, under a business associate agreement.

03

Review each claim

Every claim in the sample is checked against the note and the payer rule.

04

Score and group the results

Findings are grouped by cause, such as documentation, coding, modifiers, or payment, so you can see patterns.

05

Walk through it with you.

We go through the findings with you and your providers and agree on what happens next.

Where the findings point to a process problem, the fix usually sits in your revenue cycle management.

What We Check on Every Claim: Coding, Modifiers, Charges and Payments

The audit checks the code, the modifier, the diagnosis, the charge, and the payment against the note. This is our medical billing audit checklist, and errors cost money in both directions.

Finding	What it looks like	What the audit does with it
Overcoded E/M	Level billed is higher than the medical decision-making or time in the note supports.	Score the note against the level. Quantify the difference. Flag the repayment question.
Undercoded E/M	Level billed is lower than the note supports.	Quantify the missed revenue. Feed it back to the provider.
Unbundled services	Two codes billed separately that a payer edit treats as one service.	Check the edit pair and whether the documentation supports a separate service.
Modifier errors	Modifier 25 or 59 on a claim with nothing in the note that shows a separate service.	Read the note. Remove or support the modifier.
Missed charges	A documented service that never reached a claim.	Compare schedules, census, or notes to claims billed.
Duplicate billing	The same service billed twice, or by two providers on the same date.	Check claim history and payer rules.
Diagnosis linkage	Diagnosis does not support the service, or it is unspecified when the note gives more detail (ICD-10-CM).	Check linkage and specificity against the note.
Documentation gaps	Missing, unsigned, or thin notes.	Flag them. A service the record does not support cannot be defended.
Place of service or provider mismatch	Wrong place of service code, or a claim under the wrong rendering provider.	Check against the encounter and enrollment.
Timely filing misses	Claims filed after the payer deadline.	Find where the delay started and hand the fix to the billing process.
Underpayments	Allowed amount below the contracted rate.	Compare the remittance to the contract and route for dispute.
Credit balances	Money held that belongs to a payer or patient.	List them, with source and amount, for the practice to decide.

E/M Coding Audits: Is the Level Supported by the Note?

An E/M coding audit asks one question: does the note for that date support the level that was billed? Our medical coding audit services answer it visit by visit. Office and outpatient visit levels have been chosen on medical decision making or total time since 2021.

Hospital, emergency department, consultation, and other E/M categories followed in 2023. History and exam are documented as medically appropriate and do not set the level. A level copied forward from the day before is a classic finding, because the note for each date has to stand on its own. The same check applies in hospitalist billing and emergency room billing, where visit levels carry a lot of volume.

Payer and Government Audits, and Being Ready for One

Payers and government contractors review claims after they pay them, and a practice that has already audited itself answers faster and with less exposure.

Medicare contractors, Medicaid programs, and commercial payers can all request records and review claims after payment. A billing compliance audit run on your own schedule shows you what they would find before they ask. If a records request does arrive, we prepare the record set and the findings so you can respond. You respond to the payer, with your own counsel where needed, and we do not promise any result of the review. Medicaid and commercial rules vary by state and by contract, so we read each payer’s own terms.

When an Audit Finds an Overpayment: The 60 Day Rule

Medicare and Medicaid overpayments must be reported and returned within 60 days of identification, under Social Security Act § 1128J(d) and 42 CFR 401.305.

Since 1 January 2025, CMS no longer uses the reasonable diligence standard. An overpayment is identified when you have actual knowledge of it, or act in reckless disregard or deliberate ignorance of it. For Parts A and B, the 60-day clock is suspended during a timely, good-faith investigation of related overpayments. The suspension ends when the investigation concludes and the amount is calculated, or 180 days after the initial overpayment was identified, whichever is earlier.

What to repay and when is your decision, made with your own counsel. Credit balances found in the audit are listed with their source and amount, the same way they are in our payment posting services.

What You Receive: The Medical Billing Audit Report

The medical billing audit report tells you what was found, what it cost, and what to do about it, in language you can hand to a provider.

A summary with the method stated.

Claim-level findings for every claim in the sample.

Causes grouped by type, so patterns are visible.

Notes for provider education.

A correction plan.

What to re-audit, and when.

The dollar effect of what was found, taken from the audit and never estimated.

Outsourcing Your Medical Billing Audit to A2Z

An outsourced medical billing audit puts the review in the hands of someone who did not do the billing, which is the point of an external billing audit.

When you outsource medical billing audit work, you hand over a claim sample and access to the matching records. You keep the decisions: what gets corrected, what gets repaired, and what your providers are taught. Your own staff can still run an internal billing audit between external reviews. A2Z works from your existing system with role-based access under a business associate agreement, so no migration is needed.

Billing Audits by Specialty

Mental health

Physical therapy

Internal medicine

Family practice

Hospitalist

Emergency medicine

Get Started with a Medical Billing Audit

Send us a sample of claims, and we will show you what an audit would find.

Get a Free Audit Review

Why Practices Choose A2Z for Billing Audits

Choose who audits your billing, what they check, and how they report it.

Scored against the record

Claims are checked against the medical record as well as the claim form.

Grouped by cause

Findings come back as patterns with causes instead of a bare list of errors.

Underpayments included

Underpayments and credit balances are in the report along with coding errors.

The same team can fix what it finds.

A2Z does the coding and the billing, so findings have somewhere to go.

Frequently Asked Questions (FAQs)

What is a medical billing audit?

A medical billing audit reviews a subset of your practice's claims by comparing them to your patients' medical records, the coded charges submitted for those claims, and the amounts paid to you for each claim. A medical billing audit will show you how frequently you bill incorrectly and why you do so.

What is the difference between a coding audit and a billing audit?

A coding audit will verify the accuracy of the CPT, HCPCS, ICD-10-CM codes used by a provider with reference to their documentation. In addition to reviewing these same elements as in a coding audit, a billing audit will review charges, claim details, payments made, and follow-up on claims.

What is the difference between a prospective and a retrospective audit?

A prospective audit will review all of your claims before submission to your insurance provider so that any potential issues can be resolved before the claim costs you anything. A retrospective audit is conducted on your claims after you have received your payment and will identify patterns, underpayments, and possible exposures to repayment.

How often should a practice audit its billing?

Your practice and your level of risk will determine the frequency of your audits. We do not provide a "one-size-fits-all" answer. The need for an audit increases when you bring in a new practitioner; change your EHR; switch billing companies; or if a payer requests access to your patient records.

What happens if the audit finds an overpayment?

Overpayments made through Medicare or Medicaid have to be reported and repaid to the government in no more than sixty (60) days after being discovered. This is outlined in 42 CFR 401.305. However, as of January 1, 2025, the 60-day reporting period may be put on hold for up to one hundred eighty (180) days if there is an active, good-faith investigation into other possible overpayments related to the initial overpayment. You are the only person who can determine what amount of money will be repaid and when, and you should make those decisions with the help of your legal representative.

Is an internal audit enough?

An internal billing audit can be completed quickly and inexpensively because your employees are familiar with the job; however, the person conducting the review might be so involved in the process that he/she cannot identify issues. On the other hand, an external audit provides objectivity, which is particularly relevant when a payer or compliance program requires independent verification of the billing process.

Can a billing audit find underpayments?

Yes, as long as it compares the allowable amounts for all remittances against your contracted rates. A coding-only audit will not catch these discrepancies, since the claims look right and the payments are just too small.

What do you need from us to start?

A subset of claims submitted, matching those claims to their corresponding medical records, and having the right to obtain those records via a business associate agreement. Only records that would be relevant to the audit will be requested. The specific list of records depends upon what was agreed to between you and us (i.e., which providers, payers, and/or dates) are included in the audit.