Behavioral Health Billing Mistakes That Could Be Costing Your Practice Thousands

Key Takeaways 

• CMS puts the 2024 improper payment rate for outpatient psychiatry at 16.1%, about $254.5 million, and insufficient documentation drove 78.3% of it. 

• Most behavioral health billing mistakes start at the front desk or in the note, long before a claim reaches a payer. 

• Psychotherapy codes are time-based. A session documented at 52 minutes supports 90834, not 90837, and that single minute changes the payment. 

• Add-on codes like 90785 for interactive complexity and 90833 for psychotherapy with an E/M visit are constantly missed, which is lost revenue without a single denial. 

• Medicare allows you 12 months from the date of service to file. Many commercial plans provide you far less. 

• A denial nobody works on is a write-off. Tracking denials by reason code helps practices stop repeating the same error every month. 

Behavioral health billing mistakes rarely look expensive on the day they happen. A therapist adds up to 51 minutes of time spent together to 90837. The front desk worker doesn’t check whether the client is eligible because “last month they had the same insurance.” A psychiatric nurse practitioner adds psychotherapy to an E/M visit but forgets to claim it on the bill. All of them feel small. They happen 400 times a month, so the difference between what the practice makes and what it gets is huge.  

This guide talks about the ten billing mistakes we see most often in mental health and drug use, why they happen, and how to fix them. 

Why Behavioral Health Billing Errors Can Hurt Practice Revenue 

Mental health is a field with tight limits and many patients. One clinician may see 25 or more clients a week, and sessions are billed in time units. Reimbursement per visit is lower than in procedural specialties. It’s not a rounding problem that there is a 5% mistake rate. It has to do with payroll.  

Federal statistics support this. The CMS Outpatient Psychiatric Care compliance tip said that the wrong payment rate for outpatient psychiatry services in 2024 was 16.1%, and that wrong payments were expected to cost $254.5 million. 78.3% of that was because there wasn’t enough paperwork. No paperwork led to another 17%, and wrong codes led to 2.6%.  

Pay close attention to those numbers. Wrong codes aren’t the main issue. The notes don’t show what was paid.  

Another kind of loss exists, too. With underbilling, there is never a denial. If a practice forgets an add-on code or bills for less time than the session allowed, the payer just pays less, and no one seems to notice. 

10 Common Behavioral Health Billing Mistakes

Incorrect Patient Information

A claim at the clearinghouse will be turned down if the last name is written wrong, the date of birth is switched around, or the user ID is copied from an old card. These rejections are easy to fix, but they can delay payments by days or weeks, and they add up quickly for businesses that get new clients every week.

Eligibility Verification Errors

Mental health benefits are often split up and given to a different controlled mental health group. If a client has a mental health claim, the claims may go to a different company than the one listed on their card. Checking qualifications once at entry isn’t enough. Plan-year resets, job changes, and Medicaid redeterminations can change coverage.

Missing or Incomplete Documentation

Medicare wants an individualized treatment plan that lists diagnoses and goals, as well as the type, amount, frequency, and length of services. For time-based codes, progress notes must describe the interventions used and how the client responded. The notes must also include start and end times. When audits happen, copy-forward templates that read the same way every week are a red flag.

Incorrect CPT or HCPCS Coding

Many therapists get stuck when they try to set time limits for psychotherapy. Follow the CPT rules: 90832 is for 16 to 37 minutes, 90834 is for 38 to 52 minutes, and 90837 is for 53 minutes or more. Charging $90837 for a 50-minute lesson is wrong. When you charge $90834 for a 55-minute lesson, you’re not making any money. Both of these are wrong.

Incorrect ICD-10 Coding

Clinicians use terms from the DSM-5-TR, but claims need ICD-10-CM numbers. Unknown numbers, such as F32.A or F41.9 may be okay once, but using them repeatedly without a clear reason raises questions about medical necessity. Others also won’t pay for treatment with Z codes as the main diagnosis.

Missing Modifiers

This hurts the most in telehealth. If the service is audio-video, the payer may need place of service 02 or 10, and for audio-only services, they may need modifier 93. Each payer has its own rules, and if a claim lacks the right mix of elements, it could be denied or paid at the wrong rate.

Authorization Issues

Getting permission ahead of time is usually needed for intensive therapy programs, partial treatment, psychological tests, and longer session numbers. A common mistake is when the client goes to 15 visits, the permission only covers 12, and visits 13 through 15 are denied because no one kept track of the count.

Incorrect Payer Information

The company may send claims to the medical carrier instead of the behavioral health carve-out, bill the primary plan even though the client has switched, or get coordination of benefits wrong for clients with two plans. Often, these mistakes bounce between payers for weeks.

Untimely Claim Submission

Medicare lets you file for a year after the service. Most commercial plans let you stay in the hospital for 90 to 180 days, but some Medicaid managed care plans are stricter. If a claim sits in a clinician’s notes for a month without being signed and then needs to be fixed, it could miss the window. When filed on time, rejections are generally final.

Poor Denial Follow-Up

It’s only a loss if no one works the rejection. The clearinghouse is often empty of denials because no one owns them. The claim gets old, the time to challenge runs out, and the rest of the money is lost.  

Losing revenue because of billing errors or delayed claims? 

Credex Healthcare reviews your claims, notes, and denial history to find where money is slipping out. Talk to our behavioral health billing support team. 

How Documentation Errors Affect Behavioral Health Claims 

People who pay don’t pay for sessions. They pay for sessions that are written down. The reviewer can’t be sure which psychotherapy code applies when a note doesn’t have a start and end time. This means that the claim is either downcoded or denied. If the treatment plan hasn’t been changed in eight months, it may look like therapy has no clear end point. 

In audits, the paperwork gap usually comes from one of four things: time that wasn’t recorded, language that doesn’t explain medical needs, a missing or out-of-date treatment plan, or a missing name. As long as those forms are filled in, the doctor can’t close the contact, which stops all of them.  

There’s also the issue of supervision. In most cases, doctors working toward a license at the associate level can’t bill Medicare under their own NPI. Also, business rules on controlled billing vary by plan and state. Billing under the wrong rendering provider is a documentation issue that can look like a coding issue. 

How Coding Mistakes Lead to Payment Problems 

Two main types of coding mistakes happen in behavioral health.  

That’s when you bill for 90837 when the note only supports 90834. That opens you up to an audit and could lead to a later recoupment.  

Undercoding is the second, and more practice owners do it than they think. People have missed 90785 when complexity was involved, forgotten 90833, 90836, or 90838 when a doctor provides psychotherapy during an E/M visit, or billed a normal session when crisis codes 90839 and 90840 applied, among other things. A mental health practice loses a real chunk of money every month if it doesn’t offer treatment on even a third of the visits it makes to handle medications.  

Mismatches between the diagnosis and the procedure are the other trap. If the ICD-10 code doesn’t match the billed service, the payer may not pay because it wasn’t medically necessary. 

CPT Code	What It Covers	Common Billing Mistake
90791	Psychiatric diagnostic evaluation, no medical services	Billed as 90792 by a non-prescribing clinician
90792	Psychiatric diagnostic evaluation with medical services	Used by clinicians not licensed to provide medical services
90832	Psychotherapy, 16 to 37 minutes	Billed for sessions under 16 minutes
90834	Psychotherapy, 38 to 52 minutes	Billed when the note shows 53+ minutes, which underbills the session
90837	Psychotherapy, 53 minutes or more	Billed for a 50-minute session, which over-codes it
90833, 90836, 90838	Psychotherapy add-ons with an E/M visit	Left off medication management visits that included therapy
90785	Interactive complexity add-on	Missed entirely, or billed with crisis codes, which CPT doesn’t allow
90839, 90840	Psychotherapy for crisis (first 30 to 74 min, then each extra 30 min)	Billed as a standard session instead
90853	Group psychotherapy	No attendance or individual participation noted per client

The Connection Between Billing Errors and Claim Denials 

One of three things can happen when there is a billing error: the bill is rejected, denied, or paid too little. Clearinghouse rejections are easy to fix. People who pay for things send denials, which take time for staff to fix or appeal. These are the sneaky ones because the claim looks like it was paid.  

This is how it might go. Imagine a small group practice that has seen a drop in business collections for three months in a row. There were no obvious changes. The practice moved EHRs in the spring, as shown by a study of their claims. The new system’s telehealth form starts at POS 11 with no changes. One big payer started turning down those claims because they didn’t have enough telehealth signs. Someone else paid them, but for less. There were two mistakes, one root cause, and about 90 days of lost income before someone made the connection.  

That’s why fixing each claim isn’t enough. You need to find the shape. 

How Behavioral Health Practices Can Reduce Billing Errors 

Check whether you are eligible for mental health benefits before the first session and whenever your plan year changes. Check whether a carve-out plan covers mental health claims.  

Make note forms that include start and end times, actions, the client’s reaction, and a link to the treatment plan goals. It should be the other way around: the claim should wait for a signed note.  

Find out how many visits a client has had and when their permission expires. You will be notified when a client has used two sessions too many.  

Check claims before sending them in for time-code errors, missed add-ons, telehealth modifiers, or diagnosis pairings.  

Also think ahead about telehealth rules. According to CMS’s most recent telehealth FAQs, Medicare will require in-person visits for home-based mental health telehealth after December 31, 2027. Start tracking in-person visit dates now, and you won’t have to scramble later. 

A Monthly Audit for Behavioral Health Billing Mistakes 

Pull between 10 and 20 claims at random for each clinician every month. Check that add-ons were recorded, that the diagnosis supports the service, and that each denial is reviewed by reason code. Soon, patterns start to show up. One doctor or nurse rounds up. Another never sends a bill to 90785. Fix the behavior, not just the claim. 

Provider Prevention Checklist 

• Make sure you are eligible and know your perks before every visit. 

• Check the status of previous authorizations and notices of extension every week. 

• Check the correctness of CPT codes every month 

• Use standard templates for paperwork that are ready for payers 

• Connect every session note to a clear statement of medical need 

• Send in claims every day instead of once a week. 

• Keep a reference book for payer-specific requirements 

• If you are denied, appeal right away instead of writing them off. 

• Check the age of accounts receivable once a week. 

• Check core billing KPIs once a month and act on trends 

When Should You Consider Outsourcing Behavioral Health Billing? 

When denials keep coming in faster than your team can handle, when days past due keep rising, or when your biller is also your receptionist and scheduler, it makes sense to outsource. When there is growth, like when there are more prescribers, more IOPs, or more states with different Medicaid programs, this also makes sense. 

How to Choose a Behavioral Health Billing Partner 

Ask straightforwardly. The team should know the rules for therapeutic time, as well as the add-on codes and crisis codes. Do they deal with state Medicaid rules and carve-out plans where you work? Is it also their job to make sure that new mental health professionals don’t see clients before they’re enrolled? 

Find out how they report. Every month, you should see rejections by reason code, receivables that are past due by payer, and collections by doctor. See how quickly a turned-down claim is reviewed. Don’t give up if the answer isn’t clear. 

Want someone else to look over your claims? Credex Healthcare will look over your bills for free if you use their services for mental health or drug abuse. Check out our revenue cycle services for mental health. 

FAQs 

What are the most common behavioral health billing mistakes? 

Common paperwork mistakes include incorrect therapist time codes, missed add-on codes, qualifying errors, missing authorizations, and rejections that go unaddressed. 

Why do behavioral health claims get denied? 

Most of the time, it’s because of missing or inadequate paperwork, qualifying issues, coding errors, missing authorizations, or late filing. Our guide on why mental health claims are denied goes into detail about each reason. 

How can behavioral health practices reduce billing errors? 

Before each episode of care, make sure the patient is eligible. Use note forms that record time and medical needs. Scrub claims before sending them in, and review a sample of claims each month. 

How does incorrect coding affect behavioral health reimbursement? 

Overcoding increases the chance of audits and recoupments. If you miss add-on codes or bill for a lower time tier, this is called undercoding, and it stops payment without a rejection. 

Should behavioral health practices outsource billing? 

Consider whether rejections and old accounts receivable keep rising, or whether healthcare staff is also billing for patients. 

How can documentation errors affect behavioral health claims? 

After an audit, missing session times, out-of-date treatment plans, or unsigned notes can lead to downcoding, denials, or demands for repayment. 

Final Thoughts 

Most billing mistakes in mental health aren’t caused by one big mistake. A sped-up session, skipping the eligibility check, or leaving a denial in the queue are all small habits that happen hundreds of times. The practices that get a lot of support aren’t magic. They make sure the person is eligible, write notes that match the code, and review denial rates every month. 

Are you ready to stop losing money on billing mistakes that you can avoid? 

Credex Healthcare helps mental health facilities clean up claims, recover money taken by mistake, and keep payments coming in. Sign up for a free review of your mental health billing.