The Definitive GT Modifier Telehealth Billing Guide for Behavioral Health (2026)

If you've ever had a telehealth claim denied because of a missing or incorrect modifier, you already know how frustrating — and expensive — modifier errors can be. The GT modifier is one of the most commonly misapplied billing codes in behavioral health, and in 2026, the rules around it have shifted just enough to catch even experienced billers off guard.

This guide cuts through the confusion. Whether you're a solo therapist billing your own claims, an LCSW at a group practice, or an office manager juggling credentialing and billing across a roster of providers, you'll walk away knowing exactly when to use the GT modifier, when not to, which payers still require it, and how to protect yourself in an audit.

Let's get into it.

What Is the GT Modifier?

The GT modifier ("via interactive audio and video telecommunications systems") is a two-character billing modifier appended to a CPT code to indicate that a service was delivered via live, two-way video. It was originally introduced by CMS to distinguish real-time telehealth from store-and-forward services (asynchronous communication like secure messaging or recorded video).

When you add GT to a CPT code — say, 90837-GT for a 60-minute psychotherapy session — you're telling the payer: "This session happened in real time, face-to-face, over a video platform."

Simple concept. Complicated execution.

GT Modifier vs. 95 Modifier: Know the Difference in 2026

This is the question we get most often, and it matters a lot.

| Feature | GT Modifier | 95 Modifier | |---|---|---| | Used by | Medicare (legacy) + some commercial payers | Medicare Advantage, Medicaid (many states), most commercial payers | | Meaning | Synchronous audio-video telehealth | Synchronous audio-video telehealth | | Origin | CMS legacy modifier | AMA-defined modifier (introduced 2017) | | 2026 Status | Still required by some payers; largely replaced by 95 for Medicare fee-for-service | Preferred by most payers including UnitedHealthcare, Aetna, Cigna, BCBS | | Audio-only services | Not applicable | Not applicable (use modifier 93 for audio-only) | | Place of Service code | Pair with POS 02 (telehealth, patient not at home) or POS 10 (patient at home) | Pair with POS 02 or POS 10 |

The bottom line for 2026: Medicare fee-for-service has largely transitioned away from requiring GT for most services, but many Medicaid programs and commercial payers still mandate it. Never assume — always verify with the specific payer's telehealth billing policy.

Does Medicare Still Require the GT Modifier in 2026?

Here's where things get nuanced. During the COVID-19 Public Health Emergency (PHE), CMS made sweeping telehealth flexibilities permanent or extended them through various legislative acts. As of 2026:

Traditional Medicare (fee-for-service): For most behavioral health CPT codes, CMS now relies primarily on Place of Service (POS) codes 02 and 10 to identify telehealth claims. The GT modifier is no longer strictly required for Medicare FFS claims — but it's also not rejected when included. Many billing systems still add it by default, which is fine.
Medicare Advantage (MA) Plans: This is where it gets messy. MA plans set their own telehealth policies within CMS guidelines. Plans like Humana, UnitedHealthcare Medicare Advantage, and Aetna Medicare Advantage may still require GT, 95, or both. Check each plan's provider manual.
Medicaid: Varies dramatically by state. States like Texas, Florida, and Ohio Medicaid programs continue to require GT on telehealth claims. Others have fully transitioned to POS-based identification.

Pro tip: Run a payer-specific eligibility check before the first telehealth session with any new patient. Billing errors caught before claim submission cost you nothing. Billing errors caught after a denial — or worse, an audit — cost you time, money, and credibility.

Which Behavioral Health CPT Codes Use the GT Modifier?

Any CPT code that can be delivered via telehealth may need the GT modifier, depending on the payer. Here are the most common behavioral health codes you'll be pairing with GT:

Psychotherapy Codes

90832 – Psychotherapy, 30 min
90834 – Psychotherapy, 45 min
90837 – Psychotherapy, 60 min
90847 – Family psychotherapy with patient present
90846 – Family psychotherapy without patient present
90853 – Group psychotherapy

Evaluation & Management (E/M) + Psychotherapy Add-Ons

99213-GT / 99214-GT – Office E/M codes (for psychiatrists billing E/M)
90833 – Psychotherapy add-on, 30 min (with E/M)
90836 – Psychotherapy add-on, 45 min (with E/M)
90838 – Psychotherapy add-on, 60 min (with E/M)

Psychiatric Diagnostic Evaluations

90791 – Psychiatric diagnostic evaluation (no medical services)
90792 – Psychiatric diagnostic evaluation with medical services

Crisis Codes

90839 – Psychotherapy for crisis, first 60 min
90840 – Psychotherapy for crisis, each additional 30 min

Substance Use Disorder

H0004, H0006, H2019 – Depending on state Medicaid coverage for telehealth SUD services

Place of Service Codes: The Other Half of the Telehealth Billing Equation

The GT modifier doesn't work in isolation. You must also use the correct Place of Service (POS) code:

| POS Code | Description | When to Use | |---|---|---| | POS 02 | Telehealth – patient not in their home | Patient is at a clinic, hospital, or other facility | | POS 10 | Telehealth – patient in their home | Patient is at their residence (most common for behavioral health) | | POS 11 | Office | In-person session only — do NOT use with GT | | POS 53 | Telehealth (store and forward) | Asynchronous only — rarely used in behavioral health |

A mismatch between your POS code and modifier is one of the top reasons telehealth claims get flagged. If you bill POS 11 with a GT modifier, expect a denial or audit inquiry.

Top 5 Reasons GT Modifier Claims Get Denied

Based on real-world behavioral health billing patterns, here's where practices lose money:

Wrong modifier for the payer. Using GT when the payer wants 95 (or vice versa) triggers an automatic denial with most clearinghouses.
Missing POS code or wrong POS. Billing POS 02 when the patient was at home (should be POS 10) is increasingly flagged, especially by Medicare Advantage plans conducting post-payment audits.
Non-covered telehealth service. Not every CPT code is approved for telehealth delivery by every payer. Group therapy (90853) in particular has inconsistent telehealth coverage across payers.
Provider not enrolled as a telehealth provider. Some payers require a separate telehealth credentialing attestation. You can be fully credentialed but still have telehealth claims denied if that attestation is missing.
Documentation doesn't support telehealth delivery. Your clinical notes must explicitly state the session was conducted via video, the patient's location, and that informed consent for telehealth was obtained. Notes that could have been written for an in-person session create audit vulnerability.

GT Modifier Billing by Major Payer: 2026 Quick Reference

| Payer | Modifier Required | POS Required | Notes | |---|---|---|---| | Medicare FFS | Not required (GT accepted) | POS 02 or 10 | Relies on POS for identification | | Medicare Advantage (Humana) | GT or 95 (plan-specific) | POS 02 or 10 | Verify per plan ID | | Medicaid (varies by state) | GT (many states) | Varies | TX, FL, OH still require GT | | UnitedHealthcare Commercial | 95 preferred | POS 02 or 10 | GT may still process | | Aetna | 95 | POS 02 or 10 | GT rarely accepted for commercial | | Cigna | 95 | POS 02 or 10 | Consistent 95 requirement | | BCBS (varies by plan) | GT or 95 | POS 02 or 10 | Check local plan policy | | Optum/UBH | 95 | POS 02 or 10 | GT may trigger manual review | | Tricare | GT | POS 02 or 10 | GT still actively required | | Molina Healthcare | GT | Varies | Medicaid managed care — confirm state |

Telehealth Documentation Requirements: What Your Notes Must Include

Billing a GT modifier without proper documentation isn't just a claim problem — it's a compliance problem. If your practice is audited, the question won't just be "Did you use the right modifier?" It'll be "Can you prove this session actually happened the way you billed it?"

Here's what every telehealth session note must include to support a GT modifier claim:

✅ Explicit statement that the session was conducted via synchronous video (not phone, not messaging)
✅ Patient's location at the time of the session (city and state minimum)
✅ Provider's location at the time of the session
✅ Confirmation of telehealth informed consent (either in the note or referenced with a signed consent form date)
✅ Technology platform used (some payers and state boards require this)
✅ Session start and end time (especially for time-based codes like 90837)
✅ Clinical content that aligns with the CPT code billed — a 90837 note must document 53+ minutes of psychotherapy, not a 20-minute check-in

Vague notes like "Pt seen via telehealth, discussed coping strategies" won't survive an audit. Your documentation should tell the clinical story of the session in enough detail that an outside reviewer can verify the service occurred as billed.

Audio-Only Telehealth in 2026: Don't Use GT

This is a common mistake, especially for practices serving patients with limited technology access. The GT modifier is for video only. If you delivered a session via telephone (audio-only), you need to use:

Modifier 93 (synchronous telemedicine service rendered via telephone or other real-time interactive audio-only communications technology)
Appropriate audio-only CPT codes where applicable

Medicare has extended audio-only behavioral health coverage through 2026 legislative provisions, but coverage and reimbursement rates differ significantly from video telehealth. Many commercial payers do not cover audio-only behavioral health services at all, or require prior authorization.

Never append GT to a telephone-only session. That's upcoding, and it creates serious compliance exposure.

Group Practice Compliance Considerations

If you're running a group practice with multiple telehealth providers, modifier errors compound quickly. A single misconfigured billing template can generate dozens of incorrect claims per month. Here's how to protect your practice:

Create payer-specific billing templates that auto-populate the correct modifier based on payer and service type.
Audit telehealth claims monthly — pull a sample of GT-billed claims and match them against session notes to verify documentation completeness.
Train every clinician on documentation standards, not just the billing team. The therapist writing the note is your first line of audit defense.
Keep a telehealth credentialing log — track which payers have received and approved telehealth attestations for each provider on your roster.
Use AI-assisted documentation tools that flag incomplete telehealth documentation before the note is finalized.

GT Modifier and the Originating Site Rule: Still Relevant in 2026?

The originating site rule — which historically required Medicare patients to be at an approved clinical facility to receive telehealth — was essentially suspended during the PHE and has remained relaxed for behavioral health through ongoing legislative extensions. As of 2026:

Mental health services can be delivered to patients at home (POS 10) under Medicare for behavioral health providers.
The Rural Health Clinic (RHC) and Federally Qualified Health Center (FQHC) originating site rules have specific carve-outs for mental health telehealth — review CMS guidance if you bill through these entity types.
The 6-month in-person requirement for Medicare telehealth mental health services (established under the Consolidated Appropriations Act) has been extended and modified — confirm current status with CMS as 2026 legislation continues to evolve.

Frequently Asked Questions (FAQ)

1. Can I use the GT modifier and the 95 modifier on the same claim?

No. These modifiers serve the same functional purpose — identifying synchronous telehealth — and should never appear together on the same service line. Using both will likely trigger a rejection. Choose the one required by the specific payer.

2. What happens if I forget to add the GT modifier to a telehealth claim?

If a payer requires GT and it's missing, you'll typically receive a denial with a remark code like CO-4 (the procedure code is inconsistent with the modifier) or CO-B7 (provider not certified). You can correct and resubmit within the payer's timely filing window.

3. Does the GT modifier affect my reimbursement rate?

For most payers, telehealth reimbursement rates are now equivalent to in-person rates for behavioral health services — a major win from PHE-era policy changes that have largely been made permanent. However, a small number of payers still apply a telehealth differential. Check your fee schedules.

4. Do I need the GT modifier for telepsychiatry medication management sessions?

Yes, if the payer requires it for telehealth. Medication management billed under E/M codes (99213, 99214, 99215) combined with psychotherapy add-on codes should all carry the appropriate telehealth modifier if delivered via video.

5. My state Medicaid plan changed its telehealth billing requirements. How do I stay current?

Sign up for your state Medicaid program's provider bulletins and newsletter. Changes to modifier requirements are almost always announced in these communications 30–90 days before taking effect. Your billing clearinghouse may also push payer alerts.

6. Is the GT modifier required for initial psychiatric evaluations (90791/90792) done via telehealth?

Yes, if the payer requires it. Psychiatric diagnostic evaluations conducted via video should carry the GT modifier (or 95, depending on payer) along with POS 02 or 10. These are among the most closely scrutinized codes in behavioral health audits, so documentation quality is critical.

7. What's the risk of using the wrong telehealth modifier versus no modifier at all?

Both create problems, but in different ways. A wrong modifier typically causes an immediate denial that you can correct. Missing documentation to support any telehealth claim — regardless of whether the modifier is correct — is what creates serious audit and compliance risk. Claims that survive the denial process but lack supporting documentation are refund liability.

The Bottom Line

The GT modifier isn't going away in 2026 — but its role is shifting. Medicare FFS has moved toward POS-based identification, while Medicaid programs and certain commercial payers still require it explicitly. The practices that thrive in this environment are the ones that:

Know their payer mix cold
Build the right billing templates
Produce documentation that can survive scrutiny
Audit themselves before someone else does

Telehealth is now a permanent part of behavioral health delivery. Your billing infrastructure needs to be just as permanent and just as solid.

How Mozu Health Helps You Get Telehealth Billing Right

At Mozu Health, we built our AI-powered clinical documentation platform specifically for behavioral health providers who can't afford billing errors or audit exposure.

Here's what that means in practice:

Smart documentation prompts that ensure your telehealth notes include every required element — patient location, provider location, consent confirmation, session duration, and clinical content aligned to the billed code
Modifier and POS flagging that catches mismatches before a claim ever leaves your practice
Audit-ready note formatting that organizes documentation the way reviewers and payers expect to see it
HIPAA-compliant, built for behavioral health — designed for therapists, LPCs, LCSWs, LMFTs, and psychiatrists, not retrofitted from a general EHR

Whether you're a solo practitioner doing your own billing or a group practice managing 20+ providers, Mozu Health takes the documentation burden off your plate so you can focus on your clients — not your compliance risk.

👉 Try Mozu Health free at mozuhealth.com — and see how AI-powered documentation can protect your practice in 2026 and beyond.

This guide is intended for educational purposes and reflects billing guidance as of early 2026. Payer policies change frequently. Always verify requirements directly with individual payers and consult a certified medical billing professional or healthcare attorney for compliance-specific advice.

GT Modifier Telehealth Billing Guide 2026