Guide

First session, no diagnosis yet: 90791 or 90837?

Summary

Nothing in the Medicare contractor coverage policy for psychiatric evaluation and psychotherapy makes 90791 the required code for a first therapy session. 90791 is the psychiatric diagnostic evaluation, and it is where a tentative diagnosis gets established, which is why it fits most intakes. 90837 is timed psychotherapy, and that contractor policy presumes an active treatment plan tied to an identified condition. Choose by what the session was, not by the fact that it came first.

By Gale Editorial · Updated 2026-09-01. Every figure cited to a dated source. How we write.

Does the first session have to be 90791?

No. Nothing in the Medicare contractor coverage policy for psychiatric diagnostic evaluation and psychotherapy makes 90791 a precondition for billing a first visit, and nothing in it assigns a code to an hour on the grounds that the hour came first. The policy describes two different services. Most first sessions are the evaluation, which is why 90791 usually fits.

The psychiatric diagnostic evaluation is the code's own subject. One Medicare contractor's coverage policy lists what the service includes: an integrated biopsychosocial assessment, the establishment of a tentative diagnosis, and an evaluation of the patient's ability and willingness to participate in the proposed treatment plan 1. It can be conducted once, at the onset of an illness or suspected illness 1.

A suspected illness is enough to open one.

The same policy conditions psychotherapy on something a first hour often does not have yet. Psychotherapy has to be provided as an integral part of an active treatment plan for which it is directly related to the patient's identified condition or diagnoses 1. Where nothing is identified at the point the session starts, a timed psychotherapy code is being asked to describe the work that does the identifying.

But read the jurisdiction line before carrying any of that to a commercial claim. The coverage determination and its companion billing article are First Coast Service Options' policy for Florida, Puerto Rico and the U.S. Virgin Islands under Medicare Part B, not a national rule and not a payer contract. What is national is thinner and still worth holding: CMS's own March 2026 education booklet groups 90791 and 90792 as psychiatric diagnostic evaluation and puts the psychotherapy codes 90832 through 90838 in a separate family 2.

What the evaluation has to contain

The policy lists what the evaluation has to contain, and a confirmed diagnosis is not on the list. It calls for an integrated biopsychosocial assessment, the establishment of a tentative diagnosis, and an evaluation of the patient's ability and willingness to participate in the proposed treatment plan 1. The documentation it expects names a multi-axis diagnosis or diagnostic impression list, including a problem list 1.

That wording answers the worry underneath the question: a clinician who ends the hour holding three impressions, a problem list and a plan to meet twice more has performed the service the code names. The evaluation is where the tentative diagnosis gets formed, so walking in without one is the ordinary case.

Repeating it is a narrower question. The same policy allows the same provider to repeat the evaluation after an extended hiatus in treatment, an inpatient admission, or a significant change in the patient's mental status 1. That is one contractor's medical necessity standard rather than a national frequency edit. No source here states a limit shaped like once per patient per provider per year, and a commercial plan's answer sits in that plan's published behavioral health policy.

When 90837 is the right code for a first visit

When the hour was psychotherapy against a plan that already exists. A transfer from another clinician with records in hand, a client returning to a chart you already hold, a first visit where the condition was identified elsewhere and treatment began immediately: those are psychotherapy hours, and the timed codes govern them. Time decides which one, and the note has to carry the time.

The bands come from the same Medicare billing article, which tells the clinician to report the code closest to the actual time spent 3:

Documented timeIndividual psychotherapyWith an E/M service
16 to 37 minutes9083290833
38 to 52 minutes9083490836
53 minutes or more9083790838

Start and stop times or total times must be documented for 90832, 90834 and 90837 3. A note saying the session ran an hour, with no times in it, is the one that loses on review.

The 30, 45 and 60 minutes printed in the descriptors are not exact thresholds. APA Services reads the coding manual as allowing some flexibility there, with the time table deciding the code 4. On those bands a 53 minute session reaches 90837 and a 50 minute session does not 3. The bands behind 90832, 90834 and 90837 do the work the round numbers appear to do.

Two neighboring questions get their own answers. Sessions that run well past the top band, extended EMDR sessions and intensives among them, raise their own comparison. A prescriber's first visit runs on the evaluation and management side, where 99214 plus 90833 versus 90837 is the choice being weighed.

What goes in the diagnosis field when there isn't one

A symptom code. The FY 2026 outpatient guidelines allow a first-listed diagnosis to be a symptom when a diagnosis has not been established by the provider, and they bar coding anything documented as probable, suspected, questionable, rule out, compatible with, consistent with, or a working diagnosis 5. Code the condition to the highest degree of certainty reached in that encounter, which after an evaluation is often a presenting symptom.

These are the outpatient guidelines, and the document flags that outpatient reporting differs from inpatient and psychiatric hospital practice 5. Whether a given payer's covered diagnosis list accepts the symptom code you chose is a separate question with a lookup rather than a rule: the Medicare version is your MAC's billing and coding article for that code, and the commercial version is the plan's published behavioral health policy read alongside your contract.

The impression still belongs in the chart. What the guidelines keep off the claim is the unconfirmed diagnosis, and the differential recorded in the note is part of what supports the evaluation billed.

The self-pay version of the same question

A self-pay client's good faith estimate asks for diagnosis and service codes before the session that produces them. The federal rule requires the estimate to list the items and services expected, with the applicable diagnosis and service codes, the provider's name, national provider identifier and taxpayer identification number, and the disclaimers the rule specifies 6. Any discussion of cost with an uninsured or self-pay individual counts as a request for one 6.

The clocks are short, running on one or three business days depending on how far ahead the appointment sits 6. A rate quoted out loud still has to be issued in writing, and a copy has to be provided on request for six years 6.

So the good faith estimate diagnosis field meets the same problem the claim does, one step earlier: it asks for a code before the hour that produces it. The service code for a planned intake is knowable the day someone books, which is why practices that quote a self-pay rate tend to settle both codes once, in the scheduling script that carries a client from first call to first session.

If the claim comes back denied

Make the plan name the reason in writing before rewriting anything. For non-grandfathered group health plans and issuers, the notice of an adverse benefit determination has to give the denial code and its corresponding meaning along with the plan's standard. The diagnosis and treatment codes with their meanings have to be supplied on request, and asking does not count as an appeal 7.

Ask for both in one message, then read the answer before deciding whether the problem was the code, the diagnosis field or the authorization. A plan that conditions 90837 on prior authorization, or that expects an evaluation code before it authorizes a course of psychotherapy, states that in its published behavioral health policy; that document and the fee schedule attached to your contract are the two worth having open. The 90785 add-on on family sessions draws a different denial with a different answer, and it is the one most often confused with this one.

None of this is the largest decision of the first ninety days of practice, and it is the one that recurs every week afterwards. Two things in the note settle it on review: what the session set out to establish, and the start and stop times.

Common questions

No source in the Medicare coverage material makes it a requirement. 90791 is the psychiatric diagnostic evaluation, the service where a tentative diagnosis is established, so it fits most intakes on its own terms. A first hour that was psychotherapy against a plan already in place is billed on the timed psychotherapy codes instead, with the time documented in the record.

That is the ordinary result, and the policy expects it. A psychiatric diagnostic evaluation is where a tentative diagnosis is established, and the documentation it calls for names a diagnosis or a diagnostic impression list, including a problem list. On the claim, an outpatient encounter with no confirmed diagnosis is reported with a symptom or sign code rather than a suspected one.

It can, when the hour was psychotherapy inside an active treatment plan directly related to an identified condition, which happens with transfers and returning clients. Medicare contractor guidance puts 90837 at 53 minutes or more, and start and stop times or total times must appear in the record. A first visit that spends the hour building the assessment is describing the evaluation instead.

The 30, 45 and 60 minutes printed in the psychotherapy descriptors are not exact thresholds; APA Services reads the coding manual as allowing some flexibility, with a time table deciding the code. The bands run 16 to 37 minutes, 38 to 52 minutes, and 53 minutes or more. 90791 itself is not selected by a time band in that table.

One Medicare contractor's policy allows the same provider to repeat it after an extended hiatus in treatment, an inpatient admission, or a significant change in mental status. That is a medical necessity standard for one jurisdiction rather than a national frequency rule, and it says nothing about what a commercial plan allows. Check that plan's published behavioral health policy before assuming a second evaluation pays.

The rule requires the estimate to carry the applicable diagnosis and service codes for the items and services expected, along with the provider's identifiers and the specified disclaimers. Practices generally settle the expected service code at booking, since the planned intake is known then. Any cost discussion with a self-pay client triggers the estimate, and an oral quote still has to be issued in writing.

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References

  1. 1.First Coast Service Options, Inc. (A/B Medicare Administrative Contractor, Jurisdiction N), for the Centers for Medicare & Medicaid Services (2020). Local Coverage Determination (LCD): Psychiatric Diagnostic Evaluation and Psychotherapy Services (L33252). CMS Medicare Coverage Database. link ✓The required elements of a psychiatric diagnostic evaluation (integrated biopsychosocial assessment, establishment of a tentative diagnosis, evaluation of the patient's ability and willingness to participate in the proposed treatment plan), the multi-axis diagnosis or diagnostic impression list in the expected documentation, that the evaluation may be conducted once at the onset of an illness or suspected illness and repeated after an extended hiatus, an inpatient admission or a significant mental status change, and the requirement that psychotherapy be an integral part of an active treatment plan directly related to the identified condition. Used as one MAC's Part B policy for Florida, Puerto Rico and the U.S. Virgin Islands, not a national or commercial rule.
  2. 2.Centers for Medicare & Medicaid Services, Medicare Learning Network (2026). Medicare & Mental Health Coverage. CMS Medicare Learning Network booklet MLN1986542. link ✓The national CMS grouping of 90791 and 90792 as psychiatric diagnostic evaluation, separate from the psychotherapy-with-patient family 90832 through 90838, as printed in the March 2026 booklet.
  3. 3.First Coast Service Options, Inc. (A and B MAC, Jurisdiction N), for the Centers for Medicare & Medicaid Services (2025). Billing and Coding: Psychiatric Diagnostic Evaluation and Psychotherapy Services (A57520). CMS Medicare Coverage Database — Billing and Coding Article. link ✓The psychotherapy time bands (16 to 37 minutes, 38 to 52 minutes, 53 minutes or more) and their code pairings, the instruction to report the code closest to the actual time spent, and the requirement that start and stop times or total times be documented for 90832, 90834 and 90837. Attributed in the article to one MAC's billing article.
  4. 4.APA Services, Inc. (2025). Psychotherapy Codes for Psychologists. APA Services, Inc.. link ✓That the 30, 45 and 60 minute descriptors on the individual psychotherapy codes are not exact requirements because the coding manual allows some flexibility, with the CPT time table governing code selection.
  5. 5.Centers for Medicare & Medicaid Services and National Center for Health Statistics (2025). ICD-10-CM Official Guidelines for Coding and Reporting FY 2026 (October 1, 2025 - September 30, 2026). CMS.gov (cms.gov/files/document). link ✓The FY 2026 outpatient rules for reporting a diagnosis that is not established: that a first-listed diagnosis may be a symptom, that probable, suspected, questionable, rule out, compatible with, consistent with and working diagnoses are not coded, that the condition is coded to the highest degree of certainty for the encounter, and that these outpatient guidelines differ from inpatient and psychiatric hospital practice.
  6. 6.U.S. Department of Health and Human Services (2026). 45 CFR 149.610 — Requirements for provision of good faith estimates of expected charges for uninsured (or self-pay) individuals.. Electronic Code of Federal Regulations (eCFR), Office of the Federal Register. link ✓The required content of a good faith estimate for an uninsured or self-pay individual (itemized items and services, applicable diagnosis and service codes, provider name, NPI and TIN, the specified disclaimers), that any discussion of cost counts as a request, the one and three business day issuance clocks, the written-form requirement for an oral quote, and the six-year copy-on-request duty.
  7. 7.U.S. Department of Health and Human Services (2026). 45 CFR 147.136 — Internal claims and appeals and external review processes. eCFR (Electronic Code of Federal Regulations). link ✓That for non-grandfathered group health plans and issuers an adverse benefit determination must state the denial code and its corresponding meaning plus the plan's standard, and that the diagnosis and treatment codes with their meanings are supplied on request without that request counting as an appeal.

https://www.gale.care/for-providers/pq-first-session-no-diagnosis-90791-or-90837 · 7 sources. Competitor details are cited to dated public sources and maintained as they change; figures are estimates, not commitments. Synthetic demonstration.

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