Many medical procedures can’t just be performed on the spot. They require prior authorization from the insurance payers. In fact, according to the American Medical Association, on average, practices receive 39 prior authorization requests per physician every week. That’s about 13 hours of physicians’ time wasted on paperwork.
Prior authorization confirms coverage and reimbursement before the service is delivered. However, sometimes the circumstances aren’t ideal, and there is no time for physicians to get prior authorizations for a service. This is where retro authorization comes in. It is defined as:
“Insurance approval granted by a payer for a medical service after the service has already been delivered, requested when standard prior authorization could not be obtained before treatment.”
In this guide, we will discuss what retrospective authorization is, why it is important, and what the process of getting it is. So, let’s start.
Importance of Retro Authorization in Medical Billing
Think of retro authorization as a second chance of getting your claim reimbursed. When care is delivered in an emergency, when a patient’s eligibility is confirmed only afterwards, or when a payer’s own delay pushes a decision past the date of service, retro authorization gives the provider a proper and legal channel to apply for reimbursement. If this method didn’t exist, all claims that don’t receive prior authorization would be rejected.
The importance of retro billing cannot be overlooked because if we didn’t have a claim reworking process in place, a service that was medically necessary and would have otherwise been approved would end up as an uncompensated write-off. And due to this, the patient would be left holding a long bill that should have actually gone to the insurance company.
Prior Authorization vs. Retro Authorization
Retro and prior authorization both answer the same question. However, the difference is in the timing. Here’s a quick comparison of both:
| Factor | Prior Authorization | Retro Authorization |
|---|---|---|
| Timing | Requested and approved before the service is delivered. | Requested after the service has already been delivered. |
| Use Case | Elective, scheduled, or planned services and procedures. | Emergencies, eligibility gaps, and payer or provider delays. |
| Approval Odds | Generally higher, since the payer reviews the request prospectively. | Generally lower, since payers scrutinize the reason approval was missed. |
| Documentation Needs | Standard clinical justification and coding for the planned service. | Clinical justification plus a documented explanation for why prior approval was not obtained. |
The Retro Authorization Process
Before we explain the process of retro billing, it is first important to mention that payers do not treat retro as a routine alternative to getting approval on time. It is actually reserved for circumstances where obtaining prior authorization genuinely was not possible.
The following are some examples of these situations:
- Emergency or urgent treatment.
- An unconscious or incapacitated patient.
- Retroactive member eligibility, where the patient’s coverage was confirmed or restored only after the date of service.
- Genuine administrative delays on the payer’s side.
- A change in the scope of a procedure.
Process Steps
- Review the Denial: Confirm the denial reason on the electronic remittance advice (ERA) actually points to missing or invalid authorization, not a separate coding or eligibility issue.
- Gather Documentation: Pull the physician’s clinical notes, the order for the service, and any records that explain why prior authorization could not be obtained in advance.
- Submit the Retro Authorization Request: File the request through the payer’s designated channel, portal, fax, or phone, along with a clear statement of medical necessity and the reason prior authorization was missed.
- Track the Payer’s Review: Log the submission date and the payer’s stated turnaround time, and follow up before that window closes, not after.
- Act on the Decision: If approved, resubmit or reprocess the original claim. If denied, move straight into the formal appeals process while the documentation is still fresh.
Retro Authorization Time Limits & Payer-Specific Rules
Every payer sets its own window for accepting a retro authorization request, and that window is almost always shorter than the payer’s general timely filing limit for claims. Here is an overview of the common time limits for major insurers:
| Payer | Typical Retro Window |
|---|---|
| Aetna | Commercial plans generally allow around 30 days from the date of service. |
| Cigna | As short as 1 to 15 days from the date of service through EviCore for DME. |
| UnitedHealthcare | Up to 10 business days (14 calendar days) after the date of service for select outpatient therapy authorizations. |
| Ambetter | Will generally not retro-authorize services outside of updates to existing authorizations. |
| Anthem BCBS | Tied to the retroactive eligibility determination rather than a fixed day count. |
| CareSource | Granted mainly for pending or retroactive member eligibility. |
| WellCare | Retrospective review decisions are issued within 30 calendar days of the request, not to exceed 90 calendar days from the date of service. |
Common Reasons Retro Authorization Gets Denied
Submitting a retrospective service approval request does not guarantee reimbursement. There can be many reasons for which the insurance payer might reject the claim. Take a look at the common reasons:
- Missing the payer’s deadline.
- Vague or missing clinical notes and documentation.
- Treating retro authorization as a substitute for prior authorization.
- CPT or ICD-10 codes on the retro request do not match what is billed on the final claim.
- Payers expect a genuine reason prior authorization could not be obtained, such as an emergency or an eligibility issue.
Best Practices to Improve Retro Authorization Approval
A few habits consistently separate practices with strong retro authorization approval rates from those that write off a large share of these claims:
- Know Each Payer’s Specific Rules: Retrospective authorization windows, accepted circumstances, and submission channels vary by payer and plan, so keep a current reference for every payer your practice bills.
- Build the Documentation Packet Immediately: Start gathering clinical notes and the medical necessity statement as soon as the denial is identified, rather than waiting until closer to the deadline.
- Assign Clear Ownership: Give one team member responsibility for tracking submission dates and payer turnaround times so requests do not sit unmonitored.
- Double-check Code Alignment: Confirm the CPT and ICD-10 codes on the retro request exactly match what will appear on the resubmitted claim before sending it.
- Move Quickly to Appeal: If the request is denied, submit an appeal the same week, while the supporting documentation is still complete and easy to reference.
Final Thoughts
Retro authorization simply exists because, in the real world, not all physician services can be pre-planned, nor can the administrative work always be 100% perfect. Mistakes can happen, and several circumstances can make it impossible to obtain prior authorizations. In these cases, retro billing provides a second chance at reimbursement collection.
We hope this guide has cleared up how retrospective authorization works and what it takes to get a request approved. If your practice is losing revenue to authorization-related denials, our team of billing experts at NeuraBill offers highly specialized medical billing and coding services that are guaranteed to deliver positive results.
