Concurrent or retrospective audit: what are the differences?

Among the most critical stages of the hospital revenue cycle, medical claims auditing holds a central place. It is where coding errors are identified, documentation inconsistencies are corrected and denials are avoided before they turn into losses.

But auditing well depends on more than having a qualified team. It depends on when the audit happens. Concurrent and retrospective audit respond to this challenge in different ways. The choice between them, or the combination of the two models, has a direct impact on the hospital’s billing and time to payment.

What medical claims auditing is

A technical review of the medical acts, processes and procedures related to the care provided to the patient: that is how medical claims auditing is defined. Its goal is to verify whether what was done is correctly recorded, coded and documented for billing purposes with health plans.

It is an act reserved to physicians, under Law No. 12,842/2013, and regulated by CFM (Federal Council of Medicine) Resolution No. 2,448/2025, which expanded the responsibilities of the auditor, the attending physician and the hospital’s technical director.

Among the central points of the resolution are the prohibition of denials for procedures that were previously authorized and demonstrably performed, and the requirement for direct contact between the auditor and the attending physician.

This process can take place at two different moments of the care cycle: during the hospital stay or after the patient’s discharge. This difference in timing gives rise to the two main audit models: concurrent and retrospective.

What concurrent audit is and how it works

Carried out during the patient’s hospital stay, concurrent audit follows the care process in real time. The physician auditor reviews clinical records, prescriptions and procedures while the patient is still in bed, before the claim is closed and sent to the payer.

Imagine a patient admitted for elective surgery who, on the second postoperative day, develops a complication and needs an additional procedure. If that procedure is not properly recorded in the medical record and linked to the correct code in the billing table, it simply will not be charged, or it will be denied by the payer for lack of documentary support. Concurrent audit exists to identify this kind of situation before the claim is closed.

In practice, the auditor follows the daily progress notes, cross-checks what was prescribed against what was performed and flags inconsistencies to the care and billing teams while the patient is still in the hospital. When there is a question about a course of treatment or a code, the attending physician is contacted directly, in a documented way, as required by CFM Resolution No. 2,448/2025.

The result is a cleaner claim at the end of the hospital stay, with fewer errors, fewer denials and less rework for the billing team.

What retrospective audit is and how it works

In retrospective audit, the review takes place after the patient is discharged. With the claim already closed, the auditor reviews all the documentation from the hospital stay: medical record, progress notes, reports, materials used and procedures performed, verifying whether what was billed matches what was actually provided and documented.

Think of a long ICU stay. There are days of progress notes, multiple procedures, high-cost medications, special materials. In the end, the claim sent to the payer may have dozens of items.

Retrospective audit goes over it line by line with a magnifying glass: it checks whether each procedure has the correct code, whether the materials are backed by a medical prescription, whether the daily rates are properly recorded. Any inconsistency identified at this stage can still be corrected before submission (or support a denial appeal if the payer has already done its review).

Unlike the concurrent model, retrospective audit does not interfere with the care flow. It works on the record of what has already happened, which allows a more systematic and detailed review of the entire claim. That is why it is especially useful for identifying recurring error patterns: types of procedure that are often miscoded, materials that frequently arrive without adequate documentation, or denials that repeat month after month.

This analytical view of claim history turns retrospective audit into a tool for continuous improvement of the billing process, and not just a one‑off review.

Concurrent and retrospective audit: main differences

The two models share the same goal (ensuring the hospital correctly bills what it provided), but they work at different moments and with different logic. The table below summarizes the main differences:

A simple way to tell the two models apart: concurrent audit acts before the problem reaches the payer; retrospective audit comes into play afterward. Both are necessary and, in most hospitals, they work best when applied in combination.

When to use each model (and why to combine them)

In practice, the choice between concurrent and retrospective audit is rarely an all-or-nothing decision. The two models meet different needs and, when combined, cover the billing cycle more completely.

Concurrent audit is especially suited to more complex and longer hospital stays: major surgeries, ICU stays, oncology treatments, procedures with intensive use of OPME (implants and special materials). In these cases, the volume of billable items is high, the risk of documentation inconsistency is greater and the financial impact of a denial can be significant. Having an auditor follow the process during the hospital stay reduces this risk at the source.

Retrospective audit works well for less complex claims, where the volume of hospital stays makes concurrent coverage of every case unfeasible. It also plays a strategic role in pattern analysis: by systematically reviewing closed claims, the hospital can identify which types of error repeat and where the billing process needs to be corrected.

A hospital that applies only concurrent audit may be well protected during the hospital stay but has no visibility into what slips through at claim closing. A hospital that applies only retrospective audit reacts well to denials but does not prevent them. Combining the two models resolves both limitations: concurrent audit works on prevention; retrospective audit ensures review and feeds continuous process improvement.

For hospitals with limited staff, a viable alternative is to prioritize concurrent audit for the most complex cases and reserve retrospective audit for the systematic review of the remaining volume, balancing coverage and operating cost.

Impact on the hospital revenue cycle

The choice of audit model (or the absence of a structured process) shows up directly in the hospital’s financial indicators. Two numbers from the Anahp Observatory 2025illustrate this impact well.

The accepted denial rate at hospitals monitored by Anahp (National Association of Private Hospitals) reached 1.96% of gross revenue in 2024, the highest in the recent historical series. For a hospital with gross revenue of R$ 50 million a year, that represents almost R$ 1 million in lost revenue per year. Much of that amount could be avoided or recovered with a more robust audit process.

The average time to payment, another relevant indicator, stood at 68.56 days in 2024. Claims with documentation inconsistencies or coding errors tend to be disputed by payers, which delays payment and puts pressure on the hospital’s cash flow. Concurrent audit contributes directly to reducing this time: a claim that reaches the payer without errors is less likely to be denied and is therefore paid faster.

Retrospective audit, in turn, works on recovering what has already been lost. By identifying unwarranted denials and supporting appeals with the correct documentation, the hospital recovers revenue that, without this process, simply would not come back. Over time, the systematic review of audited claims also reduces the future denial rate by correcting the process errors that caused them.

Together, the two models protect the revenue cycle on two fronts: prevention and recovery. In a scenario of squeezed margins and growing regulatory complexity, this double coverage is now a requirement of responsible financial management.

How AI strengthens medical auditing at every stage

Structuring an efficient audit process, one that covers both the hospital stay and claim closing, takes method, a qualified team and the capacity for continuous analysis. This is exactly where artificial intelligence transforms the operation.

With AI, it is possible to monitor clinical records in real time, automatically cross-check the procedures performed against billing codes, identify documentation inconsistencies and generate denial appeals with the correct grounds, all without relying exclusively on manual reviews.

Rivio applies this logic to the hospital revenue cycle end to end: from concurrent audit to denial appeals, including XML submission and payment monitoring. The result is a faster process, with fewer losses and more financial predictability for the hospital.

Frequently asked questions about concurrent or retrospective audit

What is the difference between concurrent and retrospective audits?

Concurrent audit is carried out during the patient’s hospital stay, with a focus on identifying and correcting inconsistencies before the claim is closed. Retrospective audit takes place after discharge, reviewing the complete documentation to correct errors before submission to the payer or to support denial appeals.

Does concurrent audit replace retrospective audit?

The two models are complementary. Concurrent audit reduces errors at the source, but it does not eliminate the need for a systematic review of closed claims. Retrospective audit covers what slips through during the hospital stay and contributes to the continuous improvement of the billing process.

Who can perform medical auditing in a hospital?

Medical auditing is an act reserved to physicians, under CFM Resolution No. 2,448/2025, which defines the competencies, rights and duties of the auditor, the attending physician and the technical director in the context of this process.

How does medical auditing help reduce denials?

Concurrent audit prevents coding errors and documentation inconsistencies from reaching the payer. Retrospective audit identifies unwarranted denials and supports appeals with the correct documentation. Together, the two approaches work on both preventing and recovering revenue.

What changes in practice with CFM Resolution No. 2,448/2025?

The resolution expands the responsibilities of the physician auditor and the technical director, prohibits denials for procedures that were previously authorized and demonstrably performed, and makes direct, documented contact between the auditor and the attending physician mandatory. In practice, the audit process gains clearer criteria and greater traceability of decisions.