The Definitive Therapist Billing Guide for Starting a Private Practice
So you've decided to go out on your own. Congratulations — and fair warning: the clinical part is the easy part.
Billing is where most new private practice therapists hit a wall. Not because it's impossibly complicated, but because nobody really teaches it in graduate school. You can recite the DSM-5-TR criteria for Major Depressive Disorder in your sleep, but the difference between a 90837 and a 90834 — and why billing the wrong one could cost you hundreds of dollars a month — that's the stuff you learn the hard way.
This guide changes that. Whether you're an LCSW, LPC, LMFT, psychologist, or psychiatrist just launching your practice, this is the complete billing roadmap you need — from getting credentialed to submitting clean claims to actually getting paid.
Let's get into it.
What Is Private Practice Therapy Billing, Really?
At its core, therapy billing is the process of submitting claims to insurance companies (or collecting payment directly from clients) in exchange for the mental health services you provide. Simple enough in theory. In practice, it involves:
- Credentialing with insurance panels
- Verifying patient benefits before the first session
- Selecting the right CPT codes for each service
- Writing documentation that justifies those codes
- Submitting claims through a clearinghouse or EHR
- Following up on denials and underpayments
- Maintaining compliance with HIPAA and payer contracts
Every one of those steps is a potential revenue leak. This guide covers all of them.
Step 1: Decide Your Payment Model
Before you bill a single claim, decide how your practice will collect payment. You have three main models:
In-Network (Paneled) Practice
You contract directly with insurance companies — Aetna, BCBS, Cigna, UnitedHealthcare, Optum, Magellan, Humana, etc. — and agree to their negotiated fee schedules. In exchange, you get a steady stream of referrals from their member directory.
Pros: Higher client volume, lower marketing burden, steady cash flow Cons: Lower per-session reimbursement, credentialing takes 60–120 days, heavy documentation requirements, risk of audits
Out-of-Network (OON) Practice
You don't contract with insurers. Clients pay you directly and may submit claims to their insurer for partial reimbursement.
Pros: You set your own fees, no payer contracts, less administrative overhead Cons: Smaller client pool, requires clients with PPO plans and financial flexibility
Private Pay (Self-Pay) Practice
No insurance at all. Clients pay your full fee, often $150–$300+ per session depending on your market and specialty.
Pros: Maximum autonomy, no claims, no denials, no audits Cons: Marketing-heavy, income can be inconsistent, not accessible to all clients
The hybrid model — accepting a few in-network plans while maintaining a private pay caseload — is increasingly popular. It gives you income stability while protecting part of your schedule from payer constraints.
Step 2: Get Credentialed with Insurance Panels
Credentialing is the process of applying to become an in-network provider with an insurance company. It is slow, bureaucratic, and essential.
What You Need to Get Started
Before you apply to any panel, have these documents ready:
- National Provider Identifier (NPI) — Type 1 (individual)
- CAQH ProView profile (fully completed and attested)
- Malpractice insurance certificate (most payers require $1M/$3M coverage)
- Copy of your license (and proof of supervision hours if applicable)
- W-9 and tax ID / EIN
- Curriculum vitae or work history (last 10 years)
- DEA registration (for psychiatrists prescribing controlled substances)
The CAQH Profile: Your Single Most Important Credentialing Asset
Almost every major commercial payer uses CAQH ProView to pull your credentialing data. Fill it out completely — every gap or missing document is a delay. Re-attest every 120 days without fail; an expired attestation can pause or terminate your contracts.
Which Payers Should You Apply To First?
Focus on payers with the highest market share in your region. As a general rule:
- UnitedHealthcare / Optum Behavioral Health — largest commercial insurer in the U.S.
- Anthem / BCBS (Blue Cross Blue Shield affiliates vary by state)
- Aetna / CVS Health
- Cigna / Evernorth
- Humana
- Magellan Health (manages behavioral health carve-outs for several large employers)
Also consider your state Medicaid plan and any Medicaid managed care organizations (MCOs) in your area — they often have the highest need for behavioral health providers.
Credentialing Timeline Expectations
| Payer | Average Credentialing Time | |---|---| | UnitedHealthcare / Optum | 60–90 days | | Aetna | 60–120 days | | Cigna | 45–90 days | | BCBS (varies by state) | 60–150 days | | Medicaid (varies by state) | 30–180 days | | Humana | 60–90 days |
Pro tip: Submit applications to all target payers simultaneously, not sequentially. The clock doesn't start until you apply, and you cannot see patients as in-network until you have a signed contract and effective date.
Step 3: Understand Your CPT Codes
CPT (Current Procedural Terminology) codes are the five-digit billing codes that tell insurers what service you provided. Billing the wrong code — or underbilling — is one of the most common and costly errors in private practice.
Core Therapy CPT Codes for Mental Health
| CPT Code | Service | Typical Duration | Average Reimbursement* | |---|---|---|---| | 90791 | Psychiatric Diagnostic Evaluation | 45–60 min | $150–$250 | | 90792 | Psychiatric Eval with Medical Services | 45–60 min | $200–$350 | | 90832 | Individual Psychotherapy | 16–37 min | $65–$100 | | 90834 | Individual Psychotherapy | 38–52 min | $95–$130 | | 90837 | Individual Psychotherapy | 53+ min | $120–$175 | | 90846 | Family Psychotherapy (without patient) | 50 min | $100–$155 | | 90847 | Family Psychotherapy (with patient) | 50 min | $105–$160 | | 90853 | Group Psychotherapy | 90 min | $50–$80 per member | | 99213 | Office Visit, E/M Level 3 (psychiatry) | 20–29 min | $85–$130 | | 99214 | Office Visit, E/M Level 4 (psychiatry) | 30–39 min | $115–$175 |
*Reimbursement rates vary significantly by payer, geographic location, and contract terms. These are approximate commercial insurance averages.
The 90837 vs. 90834 Decision (And Why It Matters)
This is the question that trips up new therapists most often. The difference between billing a 90834 (38–52 minutes) versus a 90837 (53+ minutes) might seem like a technicality, but it can mean $30–$50 per session. Across a full caseload of 25 clients, that's potentially $3,000–$6,000 per month in lost revenue if you're consistently undercoding.
The rule: Bill based on the face-to-face time you actually spent with the patient. Document the start and stop time in your progress note. If your sessions run 53 minutes or longer, you should be billing 90837 — and your documentation needs to reflect that.
Step 4: Verify Patient Benefits Before Every First Session
Benefits verification is not optional. It is the first line of defense against surprise denials and patient billing disputes.
What to Verify
- Plan type (HMO, PPO, EPO, POS) — HMOs often require referrals; EPOs don't cover out-of-network
- Mental health / behavioral health benefits — sometimes carved out to a separate payer like Optum or Magellan
- Deductible (individual and family) and how much has been met
- Copay or coinsurance for outpatient mental health
- Session limits (some plans cap at 30 sessions per year)
- Prior authorization requirements
- Out-of-pocket maximum
How to Verify
Call the member services number on the back of the insurance card and ask specifically about outpatient mental health benefits with CPT code 90837. Document the rep's name, the date/time, and a reference number for the call. This protects you if there's a dispute later.
Many EHRs and billing platforms now offer automated eligibility verification — use it, but always double-check edge cases manually.
Step 5: Write Documentation That Supports Your Billing
This is where clinical documentation and billing intersect — and where most audits are won or lost.
Every CPT code has medical necessity criteria that your documentation must satisfy. For outpatient therapy, that means your progress notes need to:
- Document a DSM-5-TR diagnosis (with ICD-10-CM code) that is actively being treated
- Record session start and stop times
- Describe the interventions used (CBT, DBT, motivational interviewing, etc.)
- Document the patient's response to treatment
- Note progress or lack of progress toward treatment plan goals
- Justify continued medical necessity for ongoing treatment
ICD-10-CM Codes You'll Use Most Often
| Diagnosis | ICD-10-CM Code | |---|---| | Major Depressive Disorder, recurrent, moderate | F33.1 | | Generalized Anxiety Disorder | F41.1 | | PTSD | F43.10 | | Adjustment Disorder with mixed anxiety and depressed mood | F43.23 | | Bipolar I Disorder, current episode depressed, moderate | F31.32 | | ADHD, combined presentation | F90.2 | | Alcohol Use Disorder, moderate | F10.20 | | Borderline Personality Disorder | F60.3 |
Documentation red flags that trigger audits:
- Copy-pasted or cloned notes
- No documented start/stop times
- Generic notes that don't reflect the specific session
- Missing treatment plan goals
- Diagnosis codes that don't match the clinical picture
Step 6: Submit Clean Claims and Get Paid
The Claims Submission Workflow
- Complete your session note (same day, ideally)
- Post the charge in your EHR or billing software
- Confirm patient eligibility is still active
- Submit the claim through a clearinghouse (Office Ally, Availity, Change Healthcare) or directly through your EHR
- Track claim status — most payers process within 14–30 days
- Post the ERA (Electronic Remittance Advice) when payment arrives
- Bill the patient for any remaining balance (copay, coinsurance, deductible)
Common Claim Denial Codes and What They Mean
| Denial Code | Meaning | Fix | |---|---|---| | CO-4 | Inconsistent modifier or procedure | Check modifier usage | | CO-11 | Diagnosis inconsistent with procedure | Verify DX-to-CPT match | | CO-97 | Benefit included in another service | Check for bundling issues | | PR-1 | Deductible not met | Bill patient | | PR-96 | Non-covered service | Inform patient upfront | | CO-50 | Not medically necessary | Submit medical records / appeal |
The Appeal Process: Don't Leave Money on the Table
Roughly 30–40% of denied claims can be successfully appealed. When you receive a denial:
- Identify the denial reason code
- Gather supporting documentation (progress notes, treatment plan, prior auth if applicable)
- Write a formal appeal letter citing the specific clinical rationale and payer contract language
- Submit within the payer's timely filing limit (typically 90–180 days from denial date)
Most therapists never appeal. That's thousands of dollars left uncollected every year.
Step 7: Stay Compliant — HIPAA, Audits, and Payer Contracts
HIPAA Basics for Billing
- Use only HIPAA-compliant software for storing and transmitting PHI
- Sign Business Associate Agreements (BAAs) with every vendor who handles patient data — your EHR, billing platform, clearinghouse, and even your email provider if it stores patient info
- Never transmit claim data or clinical records via unsecured email
Audit Defense
Both commercial payers and government programs (Medicare, Medicaid) conduct post-payment audits. If you're flagged:
- Don't ignore it. You have strict response deadlines.
- Pull your documentation for every audited claim and verify it supports the code billed.
- Hire a healthcare attorney or billing compliance consultant if the audit involves more than a few claims or significant repayment demands.
The single best audit defense is clean, complete, contemporaneous documentation. Write your notes like a payer reviewer will read them — because eventually, one might.
Private Practice Billing: Common Mistakes to Avoid
- Starting to see clients before credentialing is complete — you cannot retroactively bill most payers for sessions prior to your effective date
- Not collecting copays at the time of service — letting balances accumulate creates collection headaches and compliance risk
- Waiving copays routinely — this can be considered insurance fraud under federal law
- Ignoring the 90-day filing deadline — most payers won't pay claims submitted more than 90–180 days after the date of service
- Using the same note template for every session — cloned documentation is a top audit trigger
- Failing to get prior authorization when required — always check before the first session
Billing Software and Tools Comparison
| Tool | Best For | Billing Features | Price Range | |---|---|---|---| | Mozu Health | Therapists, psychiatrists, group practices | AI documentation, billing accuracy, audit defense, HIPAA-compliant | Contact for pricing | | SimplePractice | Solo therapists | Integrated billing, ERA posting | $49–$99/mo | | TherapyNotes | Solo & small groups | Notes + billing, clearinghouse built-in | $49–$59/mo | | Kareo / Tebra | Medium-large practices | Full RCM, eligibility, claims | $100–$300+/mo | | Office Ally | Budget-conscious practices | Clearinghouse, basic billing | Free–$20/mo |
Frequently Asked Questions
1. How long does it take to get credentialed with insurance companies?
On average, 60–120 days per payer — and that assumes your CAQH profile is complete and up to date. Some payers (especially Medicaid) can take 4–6 months. Submit all applications simultaneously and follow up every 2–3 weeks to avoid getting lost in the queue.
2. Can I bill insurance without an EHR?
Technically, yes — you can submit paper claims or use a standalone clearinghouse. But in practice, an EHR dramatically reduces billing errors, simplifies documentation, and helps you track claim status. The ROI is almost always positive within the first few months.
3. What's the difference between a copay and coinsurance?
A copay is a fixed dollar amount the patient pays per visit (e.g., $30 per session). Coinsurance is a percentage of the allowed amount the patient owes after the deductible is met (e.g., 20% of the $130 allowed amount = $26). Both must be collected — waiving them regularly can violate your payer contract and potentially federal law.
4. Do I need an NPI Type 2 if I'm a solo practitioner?
If you're billing as a solo practice under your own name with no employees, a Type 1 NPI is usually sufficient. However, if you have an LLC or group practice entity and want to bill under that entity's name and EIN, you'll need a Type 2 NPI for the organization. When in doubt, get both — it's free through NPPES.
5. What is "timely filing" and how do I avoid missing it?
Timely filing is the deadline by which you must submit a claim after the date of service. Most commercial payers require submission within 90–180 days; Medicare requires 12 months. Missing this deadline almost always results in a permanent denial with no appeal option. Build a weekly billing habit — don't let sessions go unbilled for weeks at a time.
6. Can I bill insurance for telehealth sessions?
Yes — telehealth coverage for mental health services has remained robust post-pandemic. Use the 95 modifier for live audio-video telehealth and confirm each payer's current telehealth policy (platform requirements, audio-only coverage, originating site rules). Rates are generally at parity with in-person sessions for most commercial payers and Medicare.
7. What's the risk of billing the wrong CPT code by mistake?
If it's a genuine error and you self-correct it, the risk is relatively low — you can submit a corrected claim. If there's a pattern of upcoding (consistently billing higher codes than supported by documentation), that becomes a compliance and potential fraud issue. This is why documentation accuracy matters so much.
The Bottom Line: Build Your Billing Infrastructure Before You See Your First Client
Most new private practice therapists underestimate how much billing infrastructure they need before they're ready to practice. Credentialing alone can take three to four months. Add in getting your NPI, setting up your CAQH profile, selecting an EHR, opening a business bank account, and getting malpractice insurance — and you're looking at a 4–6 month runway before you're fully operational.
Start early. Build systematic habits around documentation and billing from day one. And use technology that actually reduces your administrative burden rather than adding to it.
How Mozu Health Can Help
Managing clinical documentation and billing compliance on your own is exhausting — and the cost of errors is real. Mozu Health is an AI-powered clinical documentation platform built specifically for behavioral health providers: therapists, LPCs, LCSWs, LMFTs, and psychiatrists in solo and group practices.
Here's what Mozu Health helps you do:
- Generate HIPAA-compliant progress notes in minutes, not hours — with documentation that actually supports the codes you bill
- Reduce audit risk with AI-assisted documentation that flags inconsistencies before a payer does
- Improve billing accuracy by ensuring your clinical records align with your CPT and ICD-10 codes
- Save hours every week on administrative work so you can focus on your clients — and your life
You didn't start a private practice to spend your evenings writing notes. Let Mozu Health handle the documentation so you can get back to what you do best.
👉 Try Mozu Health free at mozuhealth.com — and see how much time you get back starting with your very first session.
Disclaimer: This guide is for educational purposes and does not constitute legal or billing compliance advice. Always verify current payer policies and consult a healthcare attorney or certified billing specialist for guidance specific to your practice.
