90791 or 90834: Which Code Fits Your First Session?
90791 or 90834? CPT 90791 is a psychiatric diagnostic evaluation. CPT 90834 is a 45-minute individual psychotherapy session (38 to 52 minutes). They are not two prices for the same visit. You bill 90791 to assess a new patient and 90834 to treat. This guide explains when each applies, what Medicare says about using them together and what to document. The full code reference lives in our diagnostic evaluation guide and individual psychotherapy guide.
What is the difference between 90791 and 90834?
| Code | What it is | Time |
|---|---|---|
| 90791 | Psychiatric diagnostic evaluation (no medical services) | No time range defined in CPT |
| 90834 | Individual psychotherapy | 38 to 52 minutes of face-to-face time |
Both are listed in the Medicare Mental Health booklet (MLN1986542). For the code-by-code rundown, read our CPT 90791 guide and CPT 90834 guide.
Which pays better, 90791 or 90834?
Rates come from each payer’s fee schedule and change by year, plan and state, so this page does not quote them. Medicare’s rates are searchable in the Physician Fee Schedule look-up tool. Do not pick a code for its rate. The visit decides the code: a new assessment is 90791, ongoing therapy is 90834 (or 90832 or 90837 by time). To compare 90834 against longer sessions, see 90837 or 90834.
How often can you bill 90791?
Medicare contractor article A57480 says 90791 is billed once, at the onset of an illness or suspected illness. A repeat can be allowed after a break of about six months, an inpatient admission, a significant change in mental status, or when the diagnosis needs clarifying. That is one contractor’s wording, and other Medicare contractors and commercial payers may differ.
Can you bill 90791 and 90834 on the same day?
No for Medicare. The NCCI Policy Manual, Chapter XI (2026) says psychotherapy codes are not reported with 90791 or 90792 on the same date. If the evaluation runs long, bill the evaluation and document the time. Some commercial payers treat this differently, so ask.
What to document for 90791 or 90834
- 90791: the reason for referral, history, mental status findings, diagnosis and the plan
- 90834: start and end time, interventions, response and progress toward goals
- Both: date, provider credentials and signature, and why the service was medically necessary
The documentation requirements guide cites the Medicare sources, including A57520.
What psychotherapists and psychiatrists should know about 90791 or 90834
- Psychotherapists: 90791 opens the episode of care. Start 90834 sessions at the next visit.
- Psychiatrists: when the evaluation includes medical services, 90792 is the code, not 90791. See the comparison in our 90791 vs 90792 guide.
90791 or 90834 and Medicare, private payer and state rules
- Medicare (CMS.gov): the sources above. Contractors can word frequency rules differently.
- Private payers: set their own frequency limits and authorization rules.
- State law and Medicaid: varies by state. Never apply one state’s rule to another.
90791 or 90834: common questions
What is the difference between 90791 and 90834?
90791 is a psychiatric diagnostic evaluation used to assess a patient. 90834 is individual psychotherapy lasting 38 to 52 minutes, used to treat.
Which pays better, 90791 or 90834?
It depends on the payer’s current fee schedule. The visit type decides the code, so compare rates only to plan your schedule, never to choose a code.
Can I bill 90791 and 90834 on the same date?
Under Medicare’s NCCI manual, no. Psychotherapy codes are not reported with 90791 or 90792 on the same date. Commercial payers may differ.
How often can I bill 90791?
One Medicare contractor article (A57480) says once at the onset of an illness, with repeats after about six months, an inpatient admission or a significant change. Commercial payers set their own limits.
Common 90791 or 90834 billing mistakes
- Billing 90834 at the first visit when the visit was an intake assessment
- Billing 90791 and a psychotherapy code on the same date under Medicare rules
- Repeating 90791 without a break, admission or significant change that the payer would accept
- Leaving out start and end times on the 90834 note
- Using 90791 for a prescriber visit that included medical services, where 90792 applies
Monday-morning 90791 or 90834 checklist
- Review recent intake notes and confirm each one supports a diagnostic evaluation
- Check how each payer counts repeat evaluations
- Confirm your 90834 notes show 38 to 52 minutes of documented face-to-face time
- Look for same-date 90791 and psychotherapy claims that need correcting
- Add each payer’s written frequency rule to your billing notes
How MCM South handles these claims
MCM South Medical Billing Service works only in mental and behavioral health, with solo and mid-size practices run by psychotherapists and psychiatrists. We verify insurance benefits, submit claims electronically, follow up on denied and rejected claims, file secondary claims and bill out-of-network claims for clients. Clean code selection and complete notes at the front end keep that work simple, so most of the checklist above is what we review first. If you want a second pair of eyes on 90791 or 90834 in your own claims, we can walk through it with you.
Where this applies
MCM South Medical Billing Service bills mental and behavioral health claims for psychotherapists and psychiatrists in Georgia, Massachusetts, Connecticut, Texas, Florida, New York, Colorado, Tennessee, North Carolina and Illinois. Payer rules differ by state and by plan, so confirm each rule with the payer before you bill. Ready for help? Get a free quote or schedule a consultation.
For quick reference only: verify against the current AMA CPT manual and each payer’s policy before billing. Operational billing guidance, not legal advice. Current as of last search (sources checked 9/29/26).
