Denials are one of the most common breakdowns in the billing cycle — but they’re just one stage. For the full picture of how a claim moves from session to payment, see my complete mental health billing guide.
Getting a denial back on a claim you’re confident was submitted correctly is one of the more frustrating parts of insurance billing. And if you’re newer to billing, it can feel like a dead end.
It’s not, most of the time. A lot of denials are workable — fixable errors, missing documentation, authorization issues that can be addressed after the fact. The key is knowing what you’re dealing with and responding in the way that specific payer actually requires.
That last part is where most therapists run into trouble. They look up “how to appeal an insurance denial” and find a clean, numbered process that implies a universal approach. There isn’t one. Every payer handles denials and appeals differently — different forms, different deadlines, different submission methods, different levels of review, different documentation requirements. What works with one payer may not even be accepted by another.
This guide gives you a framework for approaching denials methodically. But every time you encounter a denial, the first thing you’re doing is going back to that specific payer’s current requirements — not applying a formula.
Always verify appeal rights, deadlines, required forms, and documentation directly with each insurance payer. Requirements vary by payer, state, and provider contract and may change over time. This guide is for general educational purposes only.
First: Is This a Denial or a Rejection?
Before anything else, it’s worth being clear on what you’re actually dealing with, because a denial and a rejection are handled very differently.
A Rejected Claim
A rejected claim never made it into the payer’s adjudication process. It came back before anyone reviewed it because something in the data was wrong — a missing field, an invalid NPI format, an incorrect member ID, a formatting error that the clearinghouse or payer flagged on intake.
Rejections don’t usually require a formal appeal. You correct the error and resubmit. Because the claim was never processed, it generally doesn’t count against your timely filing window — but confirm this with the payer before assuming. The correction and resubmission process also varies by payer and clearinghouse.
A Denied Claim
A denied claim was received, entered the payer’s system, and was reviewed — but payment was not approved. Denials come with a reason code on the EOB or ERA that tells you the specific basis for the non-payment. That reason code is the starting point for every decision you make next.
Some denials are correctable by resubmitting with updated information. Others require a formal written appeal. Some require additional clinical documentation. A few can’t be resolved through appeal at all because they reflect a genuine coverage exclusion or a contractual limitation. Knowing which situation you’re in is the difference between wasting time on an unwinnable appeal and recovering a claim you should have been paid for.
The denial notice or remittance advice is where you start. Read it before you do anything else.
Why There Is No Universal Appeal Process
This is worth saying directly, because a lot of the generic “how to appeal” content out there implies a step-by-step formula that works across payers. It doesn’t.
Here’s what actually varies from payer to payer:
- Appeal deadlines — some payers require appeals within 30 days of the denial. Others allow 60, 90, or 180 days. Missing the deadline often forfeits your appeal rights entirely, and the deadline for one payer tells you nothing about another.
- Required forms — some payers have a specific appeal form that must be used. Others accept a written letter. Some require both. Submitting a letter when a form is required, or vice versa, can result in the appeal being rejected on procedural grounds.
- Submission methods — some payers want appeals submitted through their provider portal. Others require fax. Some accept mail. Some won’t accept electronic submissions for certain types of appeals. Sending an appeal through the wrong channel may mean it never reaches the right department.
- Documentation requirements — the supporting documentation needed for an authorization denial is completely different from what’s needed for a coding dispute or an eligibility issue. And what one payer considers sufficient, another may not.
- Levels of review — some payers have multiple appeal levels (first-level appeal, second-level appeal, external review). Others have one. Some require you to exhaust internal appeals before requesting external review. The path forward after a first denial looks different everywhere.
- Reconsideration vs. formal appeal — many payers distinguish between a reconsideration request (informal, often for administrative errors) and a formal appeal (more involved, requires specific process). Some require reconsideration before a formal appeal. Others go straight to appeal. This distinction affects your timeline and your documentation strategy.
None of this means appeals are impossible to navigate. It means you have to look up the specific payer’s current process every time, rather than applying a formula you learned from a different payer last month.
Common Denial Reasons — and What They Usually Mean
The reason code on the EOB or ERA is your first and most important piece of information. Here’s a breakdown of the denial types that come up most often in mental health billing and what each one typically calls for. Note that the appropriate response still depends on the specific payer’s requirements — this is a general framework, not a guaranteed fix.
| Denial Type | What It Usually Means | Common Response |
| Eligibility/coverage not active | Client’s insurance was not active on the date of service | Verify current coverage. Check for secondary insurance. If coverage lapsed without client’s knowledge, discuss self-pay options. |
| Authorization required | Services required prior authorization that was not obtained | Request retroactive authorization. Appeal with clinical documentation supporting medical necessity if retroactive auth is denied. |
| Coding discrepancy / invalid code | CPT or diagnosis code was incorrect, outdated, or doesn’t match documentation | Review the note and correct the code. Submit a corrected claim (not a new claim). Verify payer’s corrected claim process. |
| Timely filing exceeded | Claim submitted after the payer’s filing deadline | Appeal with proof of prior timely submission if available (clearinghouse confirmation). If the delay was yours, options are limited. |
| Duplicate claim | Payer already received a claim for this date of service | Check whether original claim was paid or is still pending before resubmitting. Don’t submit a third claim without clarifying status. |
| Not medically necessary | Payer determined the service does not meet their medical necessity criteria | This is one of the most common formal appeal situations. Submit clinical documentation, treatment plan, and a letter supporting necessity. Process varies significantly by payer. |
| Out-of-network provider | Therapist is not contracted with this specific plan | Verify credentialing status. Check whether client has out-of-network benefits. Appeal if there’s a credentialing discrepancy. |
| Missing or invalid information | Required field was missing or incorrect on the original claim | Correct the error and resubmit as a corrected claim per the payer’s process. |
| Coordination of benefits (COB) | Client has more than one insurance plan; primary/secondary sequencing is unclear | Confirm which plan is primary. Bill primary first and submit EOB to secondary. COB processes vary significantly by payer. |
| Benefit exhausted / visit limit reached | Client has used all covered visits under their plan for the year | Typically not appealable unless the limit itself is being disputed. Discuss self-pay or out-of-network options with client. |
This table is a general reference. The appropriate response for any denial depends on the specific payer’s current requirements, your provider contract, and the member’s plan. Always verify directly with the payer.
A Framework for Responding to Denials
Rather than a step-by-step script that implies a universal process, here’s how to think through any denial systematically — with the understanding that every payer requires you to look up their specific requirements before you act.
Read the Denial Completely Before Doing Anything
This sounds obvious, but it’s the step most often skipped. The EOB or ERA contains the denial reason code and often additional notes that explain exactly what the payer is citing. Misreading or skimming the denial and assuming you know the problem leads to submitting the wrong documentation, using the wrong process, or appealing something that should have been resubmitted as a corrected claim.
If the denial reason isn’t clear from the EOB, call the payer before doing anything else. Ask them specifically what caused the denial and what they need to resolve it. Take notes. Get a reference number.
Determine Whether This Calls for a Correction, Reconsideration, or Formal Appeal
Not every denied claim goes through a formal appeal process. Some situations call for correcting the claim and resubmitting. Some payers offer an informal reconsideration process for administrative errors that’s faster and less involved than a formal appeal. Others go straight to a formal process.
The distinction matters because the timelines and documentation requirements are often different for each path. Ask the payer which path applies to your specific denial before you start assembling documentation.
Verify the Payer’s Current Appeal Requirements — Every Time
Even if you’ve appealed a denial with this same payer before, verify their current requirements before you start. Appeal procedures change. Forms get updated. Deadlines get adjusted. Submission methods shift from fax to portal to mail and back again.
Specifically confirm:
- The appeal deadline from the date of the denial notice — not the date of service
- Whether a specific form is required or whether a letter is acceptable
- How the appeal must be submitted (portal, fax, mail, phone)
- What supporting documentation is required for this specific denial type
- Whether reconsideration must be requested before a formal appeal
- Whether there are page limits or formatting requirements
- Where to send documentation vs. where to submit the appeal itself (sometimes different)
Never assume that what worked with Aetna last quarter applies to UnitedHealthcare this quarter. Or that what worked with UnitedHealthcare’s commercial plan applies to their Medicare Advantage plan. They’re different processes.
Gather Only the Documentation That’s Actually Relevant
The instinct when building an appeal is to send everything — every note, every form, every piece of correspondence. That’s usually not the right call. Payers have to review what you submit, and a disorganized, overloaded appeal package can work against you.
Send what supports your specific argument for why the denial should be overturned. For a medical necessity denial, that’s clinical documentation and a letter explaining the treatment rationale. For a coding dispute, it’s the corrected claim and possibly the session note. For an authorization denial, it’s whatever the payer’s retroactive auth process requires. Match the documentation to the denial type.
Write a Clear, Factual Appeal Letter When One Is Required
Many formal appeals require or benefit from a written letter. It doesn’t need to be long, but it does need to be organized and specific. A strong appeal letter includes:
- Patient identifying information as required by the payer
- The claim number and date(s) of service being appealed
- The denial reason you’re addressing, stated clearly
- The specific basis for why you believe the denial should be overturned — factual, not emotional
- A reference to any supporting documentation included with the appeal
- Your contact information and preferred method of response
Keep the tone professional. Insurance reviewers read dozens of these. A clear, well-organized letter that gets to the point is more effective than a lengthy, frustrated one. Don’t editorialize about how unfair the denial was — focus on the facts that support reversing it.
Track Every Step
This is where a lot of appeals fall apart. The appeal is submitted and then nothing is documented — no record of when it was sent, what was included, who it went to, or when a response was expected. Then it’s three months later and there’s no way to reconstruct what happened.
For every denial you work, record:
- The date you received the denial
- The denial reason code and payer explanation
- The date you contacted the payer and what you were told
- The appeal deadline
- What documentation you submitted and when
- How you submitted it (portal confirmation number, fax confirmation, certified mail tracking)
- The date a response is expected
- Any follow-up conversations, with representative names and reference numbers
A simple spreadsheet or a note in your EHR works. The format doesn’t matter. What matters is that the record exists and you can find it.
A simple spreadsheet or a note in your EHR works. The format doesn’t matter. What matters is that the record exists and you can find it. Some practices use AI tools to keep this kind of documentation organized automatically instead — I reviewed Thera AI Hub if you want to see how that looks in practice.
Follow Up Before the Window Closes
Appeals don’t always generate automatic updates. If you submitted an appeal and haven’t heard back within the timeframe the payer quoted, follow up. Confirm the appeal was received. Ask for the current status. Ask whether additional documentation is needed.
Don’t wait until after the review window has closed to discover there was a problem with your submission. Following up consistently is one of the most effective things you can do to keep an appeal moving.
When Appealing Isn’t the Right Move
Not every denial is worth appealing, and not every denial can be appealed. Knowing when to stop is part of managing billing efficiently.
When the Denial Reflects a Genuine Coverage Exclusion
If a client’s plan simply doesn’t cover the service provided — a specific modality, a visit limit that’s been reached, a benefit that doesn’t exist under their plan — appealing that denial won’t change the outcome. The appeal process exists to challenge incorrect determinations, not to create coverage where none exists. In these situations, the conversation moves to the client: what are their options for continuing care?
When the Timely Filing Window Has Passed
If the timely filing deadline has genuinely passed and you don’t have documentation proving a prior timely submission, the realistic outcome is a write-off. Some practices spend significant time appealing timely filing denials that have no realistic path to payment. Verify whether an appeal is viable with the payer before investing time in it.
When Resubmitting Is Faster and More Appropriate
For administrative errors — a wrong date of birth, an invalid NPI, a missing modifier — correcting and resubmitting the claim is usually faster and more effective than filing a formal appeal. Some payers also specifically require corrected claims rather than appeals for certain error types. Know which path the payer wants you to take before defaulting to the appeal process.
When the Amount Doesn’t Justify the Time
This is a practical consideration that doesn’t get talked about enough. Some denials involve a small balance that would take more administrative time to appeal than the payment is worth. That’s a business decision, not a failure. Document the denial, write it off appropriately, and put your energy toward claims where the recovery justifies the effort.
Building an Internal Denial Management Workflow
One of the most important things I’ve seen in practices that handle denials well is that they have a workflow — a consistent internal process that kicks in the moment a denial comes in. They’re not starting from scratch every time or making decisions ad hoc.
An internal workflow doesn’t have to be complicated. At its core it needs to answer a few questions consistently:
- Who is responsible for reviewing denials when they come in?
- How quickly does the review happen? (Ideally within a few days of receipt, not weeks)
- Where are denials tracked? (A shared spreadsheet, a field in the EHR, a task management tool — something)
- Who is responsible for contacting the payer and verifying requirements?
- What’s the internal deadline for submitting a response, building in time before the payer’s deadline?
- Who reviews the outcome and closes the loop in the tracking system?
If you’re a solo practice managing your own billing, all of those roles are you. That’s fine — but the workflow still needs to exist. Denials that sit in a queue without a clear next step tend to age past their appeal windows without anyone noticing.
If you’re building this kind of workflow from scratch and want a more structured path, I reviewed Bill Like a Boss — it walks through denial management as part of a broader billing system, rather than leaving you to piece one together on your own.
The payer’s process will always vary. Your internal process doesn’t have to.
Frequently Asked Questions
How long do I have to appeal an insurance denial?
It depends entirely on the payer. Appeal deadlines vary widely — some payers require appeals within 30 days of the denial notice, others allow 60, 90, or 180 days. Some deadlines are measured from the date of the denial, others from the date the EOB was issued. Never assume the deadline based on what you’ve seen with another payer. Verify the current appeal window directly with each payer for each denial.
Is every denied claim appealable?
No. Appeal rights depend on the payer’s policies, your provider contract, the member’s plan, and the specific reason for the denial. Denials that reflect genuine coverage exclusions, exhausted benefits, or genuinely missed timely filing deadlines may not have a viable appeal path. Before investing time in an appeal, confirm with the payer that appeal rights exist for your specific denial type.
Should I call the payer before submitting an appeal?
Often, yes — especially if the denial reason isn’t entirely clear from the EOB, or if you’re not sure whether to correct and resubmit or file a formal appeal. Calling first can save you from going down the wrong path. Ask the payer specifically what caused the denial, what they recommend as the next step, and what documentation they’ll need. Document the conversation including who you spoke with and any reference number provided.
What’s the difference between a reconsideration and a formal appeal?
Reconsideration is typically an informal review, often used for administrative errors where the payer is willing to take another look without requiring a full formal appeal process. A formal appeal is a more structured process with specific requirements, timelines, and often multiple levels of review. Many payers require reconsideration before a formal appeal can be filed. Others go straight to formal appeals. The distinction matters because the process, documentation, and timelines are often different. Ask the payer which applies to your denial.
What if my appeal is denied?
Review the denial notice carefully to understand why the appeal was not upheld. Some payers offer multiple levels of review — a second-level internal appeal or an external review by an independent organization. Others have only one level. If external review is available and the amount warrants the effort, that may be worth pursuing. At some point, the decision becomes whether continued pursuit is a good use of your time relative to the potential recovery.
Can I appeal a timely filing denial?
Sometimes, but the circumstances are specific. If you have documented proof — a clearinghouse confirmation report, for example — showing that the claim was submitted on time and the payer failed to process it, that documentation forms the basis of a viable appeal. If the delay was genuinely on your end, most payers will not overturn a timely filing denial, and the realistic outcome is a write-off. Verify with the specific payer before investing time in an appeal you’re unlikely to win.
Can I bill the client when insurance denies a claim?
That depends on the denial reason, your provider contract, and the member’s plan. For in-network providers, most payer contracts limit your ability to bill clients for amounts beyond their normal cost-sharing (copay, coinsurance, deductible) for covered services. If a service is denied because it’s not covered at all under the plan, the situation may be different — but only if the client was properly notified in advance. This is an area where getting it wrong can create compliance issues, so verify with the payer and review your contract before billing the client for a denied claim.
How do I know if a denial is worth appealing?
Consider the denial reason, the likelihood of success, the amount involved, and the time required to build a complete appeal. A medical necessity denial with solid clinical documentation behind it is often worth appealing. A timely filing denial where the delay was yours, or a benefit exclusion denial, usually isn’t. A small-dollar denial that would require hours of documentation work may not be worth the effort even if you think you’d win. Billing is a business, and treating it like one means making realistic decisions about where to invest your time.
Final Thoughts
Insurance denials are part of working with insurance. They don’t have to derail your billing process, but they do require consistent attention and a clear head.
The single most important thing to internalize: there is no universal appeal process. Every payer does this differently, and approaching a denial with a formula you learned from a different payer is one of the most common ways to lose an appeal you could have won. The framework here gives you a way to think through any denial systematically. The specifics always come from the payer.
Approach each denial methodically: read the reason completely, verify the payer’s current requirements before you do anything else, submit only what’s relevant, track everything, and follow up. That won’t guarantee a favorable outcome every time — nothing will — but it gives you the best realistic shot at recovering claims that are legitimately payable.
And for the ones that aren’t — write them off, document what happened, and build that pattern into how you verify benefits and submit claims going forward.
Looking for a quick denial SOP? Check out my billing bundle.
This guide is for general educational purposes. Always verify appeal rights, deadlines, required documentation, and submission processes directly with each insurance payer before responding to a denial.
