Denied Claim After Prior Authorization: What to Do Next
A claim denial after you already received prior authorization is one of the most frustrating insurance situations — and one of the most winnable appeals. Here is how to challenge it quickly.
Why claims are denied even after prior authorization
Prior authorization approves that a service is covered under your plan — but the claim can still be denied afterward for reasons unrelated to the original approval. Common causes include: the procedure code billed at claims submission differs from the code that was authorized; the service was performed by a provider not listed on the authorization; the date of service fell outside the authorization window; the claim was submitted under a different member ID than the authorization; or the service was bundled or billed at a different site of care than approved. Identifying which of these applies to your denial determines the fastest correction path.
Locate and document your prior authorization evidence
Pull every piece of authorization documentation you have: the authorization number, the approval date, the authorized service description, the authorized provider name and NPI, and the effective date range. This information is typically in your insurer's member portal under "Authorizations" or in any approval letters you received. If you cannot find it, call member services and ask them to read the authorization details associated with the claim date and service. Write down the reference number for that call. You need the authorization details in writing before you submit anything.
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Compare the CPT or HCPCS codes on your denial EOB to the codes that were listed in the prior authorization. Also compare the rendering provider NPI, the facility, and the date of service. If the codes differ even slightly — for example, the authorization covered 99213 and the claim was submitted as 99214 — that mismatch is likely the denial trigger. Similarly, if the authorization named a specific provider or facility and the claim was submitted by a different entity, the insurer may deny it on those grounds even if the service itself was appropriate.
Request immediate reprocessing before filing a formal appeal
If the denial was caused by an administrative mismatch rather than a substantive disagreement, the fastest path is a reprocessing request rather than a formal appeal. Call member services, explain that the claim was pre-authorized and that you believe the denial is an adjudication error, and ask them to reprocess the claim against the existing authorization. Provide the authorization number, the claim ID, and the specific mismatch you identified. Ask for a reference number and an expected timeline. Reprocessing for administrative mismatches is often resolved faster than going through the formal appeal track.
Submit a focused written appeal if reprocessing fails
If reprocessing is declined or does not resolve the denial, file a written appeal. Your appeal packet should include: the prior authorization approval letter or portal printout with the authorization number; the denial EOB; a clear explanation of why you believe the denied service falls within the scope of what was authorized; and any provider documentation supporting the match between the authorized and billed service. Keep the appeal focused — your single argument is that the service was pre-approved and the denial is inconsistent with that approval. Attach everything that proves it.
Request a billing hold and escalate if deadlines approach
While your appeal is pending, ask the provider billing office for a hold on the account to prevent collections activity during the review period. If your appeal deadline is approaching and you have not received a decision, call member services to confirm the appeal is in the queue and ask for an expedited review if the billing timeline creates urgency. If the internal appeal is denied, file for external review immediately — authorization-related denials are frequently overturned at the external review stage when you can demonstrate that the insurer approved the service and then denied the claim for that same service.
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FAQ
Can an insurer deny a service after approving prior authorization?
Yes, for specific reasons — code mismatches, provider mismatches, expired authorization windows, and site-of-care discrepancies are the most common. But these denials are highly reversible when you demonstrate the service matched what was authorized.
What is the fastest evidence to include in this appeal?
The authorization number with approval date, the exact authorized service codes, and the denial EOB side by side. If the codes and provider match but the insurer still denied it, include that comparison as exhibit A — it is often enough to trigger a reprocessing without a full formal appeal.
What if the authorization expired before the service was performed?
Request a retroactive authorization from the insurer explaining why the service was delayed. If the delay was caused by the provider or circumstances outside your control, document that. Some plans allow retroactive authorization when good cause is shown.
What if my provider submitted a different code than what was authorized?
Ask your provider to submit a corrected claim with the authorized code and a brief explanation note. If the clinical documentation supports the authorized code, this is typically the fastest resolution. If the provider insists the higher code was correct, the dispute shifts to a medical necessity question for a different appeal track.
Sources & references
This guide is grounded in primary government sources. Verify the details that apply to your specific plan and claim.
- How to appeal an insurance company decisionHealthCare.gov (CMS)
- Internal appeals processHealthCare.gov (CMS)
- External review processHealthCare.gov (CMS)
See our sources and methodology and editorial policy for how this guidance is built and reviewed.
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