GT Modifier Deprecation 2026: What BH Practices Must Do Now

The GT modifier has been on borrowed time since CMS began its telehealth modernization push post-PHE, and 2026 is when the clock runs out for most payers. Across the roughly 50 behavioral health practices we support at Revenant Care Group, we are already seeing a split: practices that migrated to the correct Place of Service codes and modifier combinations in 2024-2025 are collecting clean, and practices that are still appending GT to their 90837s and H0004s are watching denial rates climb into the 18-22% range on telehealth claims specifically.

This post is a practical walkthrough of exactly what is changing, which CPT codes are most exposed, what the dollar impact looks like across different practice sizes, and what your billing team needs to do before January 1, 2026 claims start hitting clearinghouses. There is nothing theoretical here. These are the patterns we are tracking in live AR right now.

What the GT Modifier Deprecation Actually Means

The GT modifier (“via interactive audio and video telecommunications systems”) was the original mechanism CMS used to flag telehealth claims for Medicare. It was appended to the procedure code and paired with the patient’s originating site Place of Service code, typically POS 11 (Office) or POS 12 (Home), to signal that the service was rendered remotely.

CMS formalized the shift away from GT through the transition to POS 02 (Telehealth – Other than Home or Office) and POS 10 (Telehealth – Patient Home), which were permanently established beginning January 1, 2023. The operative principle is now that the Place of Service code carries the telehealth signal, not the modifier. For Medicare claims, GT is no longer required and in many MAC jurisdictions is actively triggering edits. For 2026, commercial payers who deferred their own policy updates are expected to complete alignment, and state Medicaid programs that received extended transition guidance are reaching their own hard deadlines.

The practical result: a claim for a 60-minute individual psychotherapy session billed as 90837 with GT on POS 11 will process incorrectly or deny outright at a growing number of payers, while the same service billed as 90837 with POS 10 (patient at home) or POS 02 (patient at a non-home location) will price and pay correctly.

The CPT Codes With the Highest Exposure in BH Telehealth

Not all codes carry equal risk. Based on the claim volume we process, the highest-exposure CPT codes for behavioral health telehealth deprecation errors are:

• 90837 (Psychotherapy, 60 minutes) – highest volume individual therapy code; frequently still billed with GT by mid-sized outpatient groups
• 90834 (Psychotherapy, 45 minutes) – second-highest denial exposure in our portfolio
• 90791 (Psychiatric diagnostic evaluation) – intake visits conducted via telehealth are being denied at elevated rates when GT is present without correct POS
• H0004 (Behavioral health counseling and therapy, per 15 minutes) – primary SUD individual therapy code; Medicaid-heavy billing makes this one especially sensitive to state-specific payer updates
• 90853 (Group psychotherapy) – often billed with legacy modifiers for telehealth groups; POS alignment errors here generate batch denials that compound quickly
• 99213 / 99214 (E&M, office/outpatient) – psychiatric medication management visits billed via telehealth still carry significant GT-related denial risk at commercial payers

If your practice is running more than 60% of visits via telehealth, which is the median we see in pure virtual BH practices we work with, every one of these codes requires an audit of your current modifier and POS configuration in your practice management system.

The Dollar Impact by Practice Size

We are not going to give you a range so wide it is meaningless. Here is what we actually see in AR impact when GT deprecation errors go uncorrected:

• Small practice (3-5 providers, ~400 telehealth claims/month): At an average allowed amount of $145 per 90837 and an 18% denial rate on telehealth claims, uncorrected modifier errors generate approximately $10,440 in monthly at-risk revenue. Annually, that is $125,000 in claims requiring rework, write-offs, or appeals.
• Mid-size group (10-20 providers, ~1,500 telehealth claims/month): The same 18% denial rate on a $145 average produces roughly $39,150 in monthly at-risk revenue, or approximately $470,000 annually before recovery costs are factored in.
• Larger BH organization (40+ providers, ~4,000 telehealth claims/month): At this volume, the exposure exceeds $1 million annually in claims requiring secondary handling, and recovery on aged telehealth denials drops significantly after 90 days.

The recovery rate on correctly appealed GT-related telehealth denials is high, typically 78-85% when the corrected claim is resubmitted with the proper POS code within the payer’s timely filing window. The problem is the administrative cost and cash flow disruption. Prevention is cheaper than recovery at every practice size.

Payer-by-Payer Variability Is the Real Complication

Medicare is the most straightforward: POS 02 or POS 10 with no GT required. The 95 modifier (synchronous telemedicine service rendered via real-time interactive audio and video telecommunications technology) is the correct modifier for Medicare when a modifier is needed at all, and it should be appended according to the specific service and MAC guidelines.

Commercial payers are where the complexity compounds. We are seeing three distinct payer behaviors right now:

• Payers that have fully aligned with CMS and are rejecting GT on telehealth claims
• Payers that still require GT in addition to POS 02 or POS 10, running a parallel requirement
• Payers that have published policy updates for 2026 but have not yet updated their own claims processing edits, creating a window where either will pass until mid-year

This means your billing team needs a payer-specific modifier matrix, not a single system-wide rule. State Medicaid plans in particular have their own transition timelines. Medicaid programs in several states are requiring the 95 modifier rather than or in addition to the POS change, and H0004 claims for SUD counseling carry state-specific requirements that diverge from Medicare’s framework. If your practice also bills drug screening codes, the payer-specific complexity in your SUD billing stack is already something you know well — the same discipline required to code G0480 through G0483 correctly for different payers applies directly to telehealth modifier management.

What Your Team Needs to Audit Before January 2026

The action list is specific. Here is what we recommend for any BH practice running significant telehealth volume:

• Pull a payer mix report segmented by telehealth claims from January through June 2025 and identify every payer where GT is still appended as the primary telehealth modifier
• Audit your clearinghouse edit rules to confirm POS 02 and POS 10 are mapped correctly in your charge capture workflow
• Update your fee schedule configurations in your PM system to default the correct POS by place of service at the time of scheduling, not at charge entry
• Build a modifier matrix by top 10 payers that documents whether each payer requires 95, GT, both, or neither alongside POS 02/10
• Run a denial trend report filtered to telehealth claims from Q3-Q4 2025 and identify the specific denial reason codes — CO-4 (modifier inconsistent with procedure) and CO-97 (service included in another service) are the most common GT-related denial indicators
• Review your MHPAEA compliance posture on telehealth parity — commercial payers that deny telehealth BH claims at higher rates than comparable medical telehealth claims may have parity violations embedded in those denials, which is a separate recovery opportunity outlined in detail in our analysis of mental health parity appeals

How We Are Handling This for Practices We Manage

For every practice in our portfolio, we have run a prospective telehealth billing configuration review against each payer’s 2026 published guidelines and our own clearinghouse edit data. Where payer policy documents are ambiguous, we have submitted direct provider inquiries and documented the responses for audit defense. We have also built claim scrubbing rules that flag any telehealth CPT code leaving the clearinghouse with GT appended unless that specific payer’s current policy explicitly requires it. The 95 modifier is now the default telehealth modifier for Medicare across all BH CPT codes in our managed practices, with POS 10 applied when the patient is confirmed to be at home at time of service and POS 02 applied for all other originating site configurations. These rules are not set once — we review them quarterly as payer policies publish updates.

Take Action Before the Volume Hits

The GT modifier deprecation is not a billing technicality. For a mid-size behavioral health group running 1,500 telehealth claims per month, getting this wrong for a full quarter represents over $117,000 in claims requiring rework before you account for the administrative cost of working aged denials. If you want a clear picture of where your telehealth billing stands right now, we offer a free 30-day denial audit that covers modifier accuracy, POS configuration, and payer-specific telehealth policy alignment across your actual claim history. You can schedule directly at our audit intake calendar. We will show you exactly what is at risk and what correcting it is worth in recovered revenue before you commit to anything.