CPT 90791 is the code for a psychiatric diagnostic evaluation without medical services. For most therapists it’s the first thing billed when a new client starts care. It also gets denied more than it should, usually for reasons that have nothing to do with the quality of the evaluation. Here is how it works and what trips practices up.
CPT 90791 description
The CPT descriptor for 90791 is “Psychiatric diagnostic evaluation.” It is reported once for the evaluation, not by the minute, and it does not include medical services such as prescribing or a physical exam. When medical services are part of the evaluation, the code is 90792 instead. The CMS Physician Fee Schedule look-up tool (opens in a new tab) shows the current Medicare payment for 90791 in each locality.
What CPT 90791 covers
A 90791 is an integrated biopsychosocial assessment. It normally includes the history, a mental status exam and your recommendations, and it can include talking with family or other sources and reviewing records. CPT does not set a minimum time for 90791, so it isn’t billed by the minute the way psychotherapy codes are. Many payers still expect the note to show roughly how long you spent.
90791 vs. 90792
The difference is medical services. 90792 is the psychiatric diagnostic evaluation with medical services, such as a medication review or prescribing. It’s billed by clinicians who can provide those services, like psychiatrists and psychiatric nurse practitioners. Psychologists, clinical social workers, counselors and marriage and family therapists bill 90791. The same provider can’t bill both on the same date.
Who can bill 90791
Any licensed clinician whose state license covers diagnostic assessment and who is credentialed with the payer. That usually means psychiatrists, psychologists, licensed clinical social workers, licensed professional counselors and marriage and family therapists. Since January 1, 2024, Medicare also lets marriage and family therapists and mental health counselors enroll and bill (see the CMS Medicare Mental Health booklet (opens in a new tab)). Commercial and Medicaid plans each set their own rules, and many route behavioral health through a separate carve-out plan, so check who actually manages the benefit.
How often you can bill it
Medicare guidance treats the evaluation as something done once, at the start of an illness or suspected illness. The same provider may repeat it after a long break in treatment, after a psychiatric inpatient admission, or when there is a significant change in the patient’s mental status. Commercial payers often go further and cap it at one per patient per provider per year or per episode of care. Look up each payer’s limit before the second one goes out.
Same-day billing rules
| Billed with 90791, same provider, same day | Allowed? | Why |
|---|---|---|
| Psychotherapy (90832, 90834, 90837) | No | NCCI edits deny the pair; bill therapy on the next visit |
| E/M visit | No | The evaluation already includes the assessment work |
| 90792 | No | Choose the one that matches what was done |
| Interactive complexity (+90785) | Yes | When the note shows a communication factor that complicated the evaluation |
These pairs are enforced through the CMS National Correct Coding Initiative (NCCI) edits (opens in a new tab), which most commercial payers also apply.
Telehealth
90791 can be done by telehealth. Medicare lets patients receive behavioral health telehealth at home, and it uses place of service 02 or 10 plus the modifiers its current telehealth rules (opens in a new tab) call for. Commercial plans don’t agree with each other on modifiers (95 or GT) or place of service, so the contract is the thing to check, not a general rule.
What the note should include
- Reason for referral and presenting problem
- History of the present illness and psychiatric history
- Substance use, medical history and current medications
- Family and social history
- Mental status exam and risk assessment
- Diagnosis with a specific ICD-10-CM code
- Recommendations and the treatment plan
- Who else provided information, if anyone
- Start and stop times (not required by CPT, but many payers look for them)
Why 90791 claims get denied
- Frequency: a second evaluation inside the payer’s limit.
- Same-day conflict: psychotherapy or an E/M billed on the same date.
- Wrong payer: the claim went to the medical plan, but a behavioral health carve-out manages the benefit.
- Credentialing: the clinician isn’t enrolled with that plan yet.
- Telehealth details: the wrong place of service or a missing modifier.
- Diagnosis: a missing or unspecified code.
Most of these are fixable before the claim ever leaves your office. Our mental health billing team checks them as part of every claim.
After the evaluation: psychotherapy codes
Ongoing sessions are billed by time: 90832 (16 to 37 minutes), 90834 (38 to 52 minutes) and 90837 (53 minutes or more). Our 90837 vs. 90834 guide covers the most common choice, and the 90785 guide explains the interactive complexity add-on.
Code rules change every year, and payer policies differ. This guide reflects general guidance at the time of writing; your payer contracts and documentation decide what is billable.
Behavioral health claims getting denied?
We can look at your recent 90791 and psychotherapy denials and tell you what is causing them.