CPT 90837 vs 90834: When and How to Bill Each (Without Triggering an Audit)

CPT 90834 and 90837 are both individual psychotherapy codes. The only structural difference is time: 90834 covers a 45-minute session (38–52 minutes of psychotherapy), and 90837 covers a 60-minute session (53 minutes or more). Reimbursement for 90837 is meaningfully higher, which is exactly why payers watch it and why practices get the choice wrong in both directions.

What are the exact time thresholds?

CPT time rules assign the code whose time is closest to the actual face-to-face psychotherapy time:

Code	Description	Documented psychotherapy time
90832	Psychotherapy, 30 minutes	16–37 minutes
90834	Psychotherapy, 45 minutes	38–52 minutes
90837	Psychotherapy, 60 minutes	53 minutes or more

Two details practices miss:

• The time that counts is psychotherapy time, not appointment-slot time. Scheduling a “60-minute session” doesn’t justify 90837 if documentation supports 48 minutes of therapy.
• There is no code above 90837 for a longer routine session. A 75-minute session is still 90837 (prolonged-service add-ons are rarely payable for routine outpatient psychotherapy, and payer policies on them vary).

When is 90837 the correct code?

When the session genuinely ran 53+ minutes of psychotherapy and the record shows it. That’s the whole rule. 90837 is not an “upgrade” for complex clients. It is the accurate code for a longer session. If your sessions consistently run 53+ minutes, billing 90834 to “stay safe” is systematic under-coding: you are donating the difference to the payer on every visit.

Why do payers flag 90837?

Because it pays more, some payers treat a high share of 90837 relative to 90834 as an audit signal. A few have historically sent “outlier” letters to clinicians whose 90837 usage sits far above peer averages. The response is not to stop billing 90837. It is to make every 90837 defensible:

1. Document start and stop times (or total psychotherapy minutes) in every note. This is the single highest-value habit in mental health billing.
2. Let the note explain the length: clinical content that plainly supports why the session ran long (crisis processing, trauma work, complexity) makes medical-necessity questions short conversations.
3. Keep the distribution honest. If some sessions are 45 minutes, bill those as 90834. A mixed, accurate distribution is your best audit defense.

Which mistake is more expensive?

Both directions cost money, but differently:

• Over-coding (90837 without documented time) risks recoupment: a payer audit can claw back the difference across every claim in the review window, plus your time fighting it.
• Under-coding (routine 53+ minute sessions billed as 90834) is the quieter loss: no letter ever arrives, but the practice loses the rate difference on every session, forever. Across a full caseload this routinely exceeds what any audit would have cost.

An honest coding review of 90 days of claims usually finds one of the two patterns. That check is part of every free billing audit we run.

How does telehealth affect 90834 and 90837?

The codes themselves don’t change. What changes is the claim wrapper: telehealth sessions need the payer’s accepted telehealth modifier (95, or GT for holdouts) and the right place-of-service code (POS 10 for a patient at home, POS 02 otherwise). Payers differ on the accepted combination and sometimes on the rate. The time thresholds and documentation rules above apply identically to virtual sessions.

The short version

• 38–52 documented minutes of psychotherapy → 90834. 53+ → 90837. Slot length is irrelevant; documented time decides.
• Record start/stop times in every note. It makes 90837 defensible and audits boring.
• Don’t defensively under-code. Accurate 90837s are money you already earned.

Related: Behavioral & mental health billing · Medical billing services