Why Are Behavioral Health Claims Denied? 10 Common Reasons and How to Fix Them

Key Takeaways 

• Every denial arrives with a Claim Adjustment Reason Code (CARC). Reading it correctly is the first step to fixing the claim. 

• In CMS’s 2024 review of outpatient psychiatry, insufficient documentation caused 78.3% of improper payments, with no documentation at 17% and incorrect coding at 2.6%. 

• A corrected claim fixes data errors. An appeal disputes a payer decision. Using the wrong path wastes weeks. 

• Medicare redeterminations must be filed within 120 days of receiving the initial determination. 

• Credentialing gaps cause denials that look like billing errors. A clinician who isn’t enrolled on the date of service can’t be paid, no matter how clean the claim is. 

• Most behavioral health claim denials repeat. Tracking them by reason code, payer, and clinician turns one-off fixes into permanent solutions. 

Behavioral health claim denials are frustrating partly because the care was already delivered. The session happened. The client showed up. And three weeks later, the remittance comes back with a two-letter group code, a number, and no payment. 

The good news is that denial is not a judgment. It is the message. Each one tells you what the payer believes is incorrect, and most can be corrected or appealed. You can correct or appeal most of them if you catch them before it’s too late. Each one informs you what the payer believes is incorrect. In this tutorial, we will cover the 10 most frequent reasons mental health and drug misuse claims are denied, how to identify them on your remittance advice, and what to do about it. 

Why Behavioral Health Claims Get Denied 

Payers don’t accept claims when anything on the claim doesn’t match their records, regulations, or supporting documentation. That list is longer in mental health than in most other areas of treatment. Benefits are often provided by a separate mental health organization. Authorizations restrict the number of sessions. Therapists might be psychiatrists, licensed psychologists, and others, with varying regulations for enrolling clients.  

The CMS data points out where the stress is. Outpatient psychiatry was underpaid incorrectly 16.1% of the time, or $254.5 million, in 2024, the CMS Outpatient Psychiatric Care compliance tip said. The codes weren’t the issue. The notes were. 

10 Common Reasons Behavioral Health Claims Are Denied

Incomplete Patient Information

• How it shows up: CARC 16 (claim missing information) or CARC 31 (unable to identify patient as insured). 

• Using a nickname instead of the legal name, a false birth date, or missing the subscriber ID will reject a claim right away. Fix the demographic information to match the insurance card, then resubmit the claim as an amended claim. Once this is corrected, it won’t happen again. Scan both sides of the card every time someone comes in for treatment.

Eligibility or Insurance Verification Issues

• How it shows up: CARC 27 (expenses after coverage ended) or CARC 22 (may be paid by another payer). 

• They occur due to gaps in coverage, plan modifications in January, and “carve-out” plans that shift mental-health coverage to another firm. This should occur before the first session and at the beginning of each plan year. If the customer has additional insurance, make sure you know the sequence of benefits before you deliver the bill.

Missing Documentation

• How it shows up: Requests for documents, then rejections if nothing comes back, or recoupment after payment and audit. 

• Medicare requires an individualized treatment plan that describes the symptoms and objectives and the kind, quantity, frequency, and duration of therapy. If the recipient requests documents and neither the plan nor the notes are signed, the claim is denied. Respond completely and promptly to record requests. Denials from late responses are easy to prevent.

Incorrect CPT or HCPCS Coding

• How it shows up: Downcoding, refusal for incompatibility of method, or request for records. 

• The classic example is treatment hours. CPT guidelines put 90832 at 16 to 37 minutes, 90834 at 38 to 52, and 90837 at 53 or beyond. A 50-minute 90837 note is not going to hold up. Billing 90792 when the clinician is not a prescriber or billing 90785 with crisis code 90839 are other common problems that CPT does not allow.

Incorrect Diagnosis Coding

• How it shows up: CARC 11 (diagnosis inconsistent with procedure) or CARC 50 (not medically necessary). 

• Time spent in therapy is a typical case. According to CPT rules, 90832 is 16 to 37 minutes, 90834 is 38 to 52 minutes, and 90837 is 53 minutes or more. A 50-minute note with the number 90837 on it won’t work.  

• Another common issue is billing 90792 for a clinician who isn’t a prescriber, or billing 90785 along with 90839, which violates CPT rules.

Missing or Incorrect Modifiers

• How it shows up: CARC 4 (procedure code inconsistent with modifier, or required modifier missing). 

• The ICD-10-CM code must be valid for the service. Denials can happen because of an unclear diagnosis during a long treatment plan, a Z code that is billed as the main code, or an old code after a diagnosis has changed. When the clinical picture changes,  

• update the description on the claim.

Missing Prior Authorization

• How it shows up: CARC 197 (precertification or authorization absent). 

• Getting psychological tests, intensive therapy programs, partial treatment, or visits that go over the number of sessions allowed by your plan usually needs to be approved first. Some payers will approve claims submitted in the past for a short time. A lot of them don’t. Track how many visits you’ve used and when each authorization ends, and request renewals before the last approved session.

Provider Credentialing or Enrollment Issues

• How it shows up: CARC B7 (provider not certified or eligible to be paid for this service on this date). 

• A new therapist starts seeing patients before the health plan finishes enrolling everyone. Or the billing record didn’t change when the practice’s location did. Medicare usually lets doctors and other health care professionals bill back up to 30 days before the registration application was sent in, but most private plans don’t. You can avoid most of these with clean behavioral health credentials.

Timely Filing Problems

• How it shows up: CARC 29 (time limit for filing has expired). 

• Medicare lets you file a claim for a year after the service. Most commercial plans give you 90 to 180 days, but sometimes they give you less time. These are almost never thrown out unless you can show that the original claim was sent out on time, which is usually possible with a clearinghouse acceptance report.

Medical Necessity or Coverage Issues

• How it shows up: CARC 50 (not deemed a medical necessity) or CARC 96 (non-covered charge). 

• Outpatient mental health services that are expected to improve the client’s condition or at least control symptoms to keep them from relapsing or having to go to the hospital are covered by Medicare. That’s not clear from notes that say “client stable, continue current plan” repeatedly for months. Connect each session to the goals in the treatment plan and keep track of progress or the reason why progress has stopped. 

Dealing with repeated behavioral health claim denials? 

Credex Healthcare can pinpoint the billing issues behind them, manage your claims, and keep payments moving.  

How to Identify the Reason for a Behavioral Health Claim Denial 

Start with either the 835 internet payment or the paper EOB. There are three things you need.  

You can tell who owns the amount by the group name. When a business has a CO, it means it can’t bill the client. Patients are responsible, or PR, which means that the client can be billed.  

The CARC tells you why the claim wasn’t paid. If there is a Remittance Advice Remark Code (RARC), it gives more information. For example, CARC 16 with a comment code may point to a missing rendering provider NPI. This tells you exactly which field needs to be fixed.  

Don’t guess based on the amount of money. For very different reasons, two claims can both show that $0 was paid.  

Use the following table as a quick reference when a remittance comes back. Match the CARC, then pick the right fix path. 

CARC	What It Means	Likely Cause in Behavioral Health	Fix Path
16	Claim lacks information	Missing NPI, wrong DOB, incomplete demographics	Corrected claim
31	Patient can’t be identified as insured	Wrong subscriber ID or name mismatch	Corrected claim
27	Coverage terminated before service	Plan lapsed or changed at plan-year reset	Re-verify, bill correct payer
22	May be covered by another payer	Coordination of benefits not updated	Update COB, rebill primary
4	Modifier missing or inconsistent	Missing telehealth modifier 95 or 93	Corrected claim
11	Diagnosis inconsistent with procedure	ICD-10 code doesn’t support the service	Corrected claim with updated diagnosis
197	Authorization absent	Sessions exceeded the approved visit count	Request retro-auth if allowed, else appeal
B7	Provider not eligible on date of service	Clinician not yet enrolled with the payer	Fix enrollment, then rebill or appeal
29	Filing time limit expired	Claim submitted past the payer’s deadline	Appeal only with proof of timely filing
50	Not medically necessary	Notes don’t show progress toward treatment goals	Appeal with notes and treatment plan

How to Fix a Denied Behavioral Health Claim 

Corrected Claim or Appeal? 

Send a new claim if the payer processed the first one correctly even though you sent bad information. Most of the time, that means resubmitting with resubmission code 7 (replacement) on the CMS-1500 and the original claim number. This is what happens when the DOB is wrong, a modifier is missing, or the place of service is wrong.  

You can appeal if you think the payer got it wrong or if you don’t agree with a medical-necessity decision. When you resubmit a claim the payer already denied, you usually get a second denial, which wastes time. 

Building an Appeal for Behavioral Health Claim Denials 

Hold on tight. Send a short letter that ties the paperwork to the payer’s policy, with the rejection notice, the claim, the signed progress note, the current treatment plan, and the progress note. If you are denied medical necessity, you must cite the relevant local coverage determination or plan policy and show how the note fits with it.  

Don’t miss the due dates. Send Medicare redeterminations within 120 days of the first determination. Commercial and Medicaid plans set window lengths, and they are usually shorter. 

How to Prevent Future Behavioral Health Claim Denials 

Rework is never better than prevention. Before care starts, make sure you are eligible and that your mental health benefits cover it. Note forms should have sections for when to start and end sessions, what to do during them, and how they relate to treatment goals. Monitor visit-count authorizations. Make sure every doctor is signed up with every client before their first paid session. Check claims for missing telehealth modifiers and time-code errors before sending them in.  

Then keep track of the results. Track every denial from the CARC, the payer, and the clinician. Imagine a therapy center that gets a lot of CARC B7 rejections every time it hires someone. The billing process has no fix. A hiring checklist holds a new clinician’s billing schedule until they are officially enrolled with a payer. 

When Should You Outsource Behavioral Health Denial Management? 

Consider outsourcing when your rejection rate keeps rising, when claims older than 90 days make up more of your past-due accounts, or when no one on staff has time to handle rejects every day. It also helps when the business is growing, like when it hires more clinicians, starts an IOP, or joins new Medicaid managed care plans. 

If a claim is denied, a good partner should look over it within a few days, report it with a reason code, and fix the process. Not just the denied claim. Find a group that handles medical billing denials and works together to fix mistakes made further up the chain. 

FAQs 

Why are behavioral health claims denied? 

Most of the time, it’s because of insufficient paperwork, qualifying issues, coding errors, missing authorization, credentialing gaps, or late filing. 

What causes mental health claim denials? 

With a behavioral health carve-out in charge of benefits, the same main problems happen, along with telehealth modifier errors, time-based code mismatches, and claims being sent to the wrong carrier. 

How do you fix a denied behavioral health claim? 

After reading the CARC and RARC, you can either resubmit an updated claim to correct data errors or appeal if you disagree with the payer’s decision. 

Can a denied behavioral health claim be appealed? 

Yes. Medicare gives people 120 days from the first decision to ask for a new one. Plans for business have their own due dates. 

How can behavioral health practices prevent claim denials? 

Early on, confirm eligibility, document time and medical necessity in every note, track authorizations, ensure the clinician is enrolled, and check claims before submitting. 

What documentation is needed for behavioral health claims? 

A written progress report that lists session times, actions, and how the client responded, along with a current treatment plan that lists illnesses, goals, and how often sessions are scheduled. 

Final Thoughts 

Denials of mental health claims tend to follow a trend. There are ten reasons that keep coming up, and you can catch almost all of them before the claim leaves your office. Read the denial code, pick the right fix, and then change the habit that made it happen.