Clinician track

How to bill ERP: CPT codes, time ranges, and payer rules

The exposure that finally does its work rarely fits the slot you booked for it. This page covers how exposure and response prevention (ERP) fits inside ordinary psychotherapy billing, and which questions belong to your payers rather than the manual.

How does ERP fit psychotherapy billing?

Exposure and response prevention (ERP) delivered as individual psychotherapy is billed with the standard timed CPT psychotherapy codes: 90832, 90834, and 90837. The descriptors name time with the patient, not the technique used, so an exposure session is coded by how long it ran. After that, the working questions are the session length you can document and what each of your payers actually covers.

Say it's 4:10 on a Thursday. The exposure you planned to close around minute 40 got traction late, and you let it run, because the work was finally happening. Now the note is open, the clock says 68 minutes, and the leftover question is a small administrative one. What goes on the claim?

The orienting fact is that the psychotherapy codes describe time, and only time. APA Services' psychotherapy billing FAQ lists the three individual codes this way:

• "90832: Psychotherapy, 30 minutes with patient"
• "90834: Psychotherapy, 45 minutes with patient"
• "90837: Psychotherapy, 60 minutes with patient"

The named minutes aren't cutoffs, by the way. In APA's words, "The CPT manual provides for flexibility by identifying time ranges in the descriptions of the three codes":

• 90832: 16 to 37 minutes
• 90834: 38 to 52 minutes
• 90837: 53 minutes or longer

And there's a floor. "The psychotherapy codes should not be billed for any sessions lasting less than 16 minutes."

So a 50-minute exposure session carries the same code as any other 50-minute psychotherapy session. The manual never asks what happened in the room, only how long you were in it.

One habit follows from that before any payer enters the picture. If time picks the code, documented time is what holds the claim up, and the FAQ is unusually direct about it: "As part of adequate documentation of patient encounters in the record, be sure to note start and stop times for every session of psychotherapy you provide. From an insurance company's standpoint, if you don't record these details, you didn't deliver the service." I'd take that at face value and write the times down every session, including the unremarkable ones.

What happens when a session runs past 60 minutes?

APA Services answers this one directly, and it names exposure therapy as its example. No CPT code exists for psychotherapy sessions longer than 60 minutes, so the guidance for sessions that require more than 60 minutes is to report 90837, the 60-minute code. Its time range is 53 minutes or longer, with no upper limit in the descriptor.

ERP is where the long-session question stops being hypothetical. Exposure work doesn't always resolve on the schedule you booked for it (the patient-side walk-through is in what ERP actually is), and where an exposure ends is a clinical decision, not an administrative one.

APA's FAQ asks the question in nearly the words you would: "Since there is no CPT code associated with psychotherapy sessions that may last longer than 60 minutes, such as exposure therapy, how do I bill for these longer services?"

The answer is worth having in full: "These codes are not intended to limit the length of time you schedule for psychotherapy. Psychologists who conduct sessions that require more than 60 minutes should report CPT® code 90837: Psychotherapy, 60 minutes with patient. Regardless of how long the session lasts, the psychologist's reimbursement will be based on the payment amount ultimately associated with 90837."

That last sentence is APA describing how the code is paid, not a promise about what your plan will cover for you, or how often. What a particular plan covers is that plan's call, and it's checkable.

One near-miss worth naming, because it looks like the long-session answer and isn't. The CPT set does contain a long-session structure with an add-on: "90839 Psychotherapy for crisis; first 60 minutes" plus "90840 Psychotherapy for crisis; each additional 30 minutes." The descriptors say what those are for. Crisis psychotherapy is a different service, and a planned exposure that ran long is not a crisis session.

What should you confirm with each payer?

Coverage rules for the psychotherapy codes are payer-specific. Medicare Administrative Contractors issue Local Coverage Determinations, commercial carriers publish their own coverage policies, and either may limit how often 90837 gets billed. APA Services advises checking your carrier's website periodically for new policies on psychotherapy billing.

The CPT manual tells you which code describes the session. What a given plan covers is a different document with a different owner, and you read it on the plan's own site.

APA's standing advice here isn't exciting, but it's right: "Generally speaking, psychologists should periodically check their insurance carrier's website for new policies on coverage and billing for services related to psychotherapy codes."

The FAQ also takes up the question you'd actually bring to it, whether payers limit how often the 60-minute code is billed relative to 90834. The answer points at the payers themselves: "Medicare Administrative Contractors issue Local Coverage Determinations (LCDs) and commercial carriers establish coverage policies for private sector health plans related to use of the psychotherapy codes."

For Medicare work that means your MAC's website, and the APA page keeps a list of them. For commercial plans it means the coverage policies published by each plan you're affiliated with.

So the confirm-with-each-payer list stays short:

• The plan's published coverage policy for the timed psychotherapy codes, read on the plan's own site.
• For Medicare, the LCDs your MAC has issued.
• Anything the plan publishes on billing 90837 versus 90834.

None of it is clinical work, and it's maybe ten minutes per payer. But I think those minutes are what keep the schedule honest, because the alternative is letting session length drift, quietly, toward whatever feels safest to bill instead of what the treatment plan calls for.

Where do the authoritative answers live?

Current CPT guidance lives in the CPT manual and on APA Services' reimbursement pages, which keep a psychotherapy-codes FAQ. Payer-side answers live in your MAC's Local Coverage Determinations for Medicare and in each commercial plan's published coverage policy. Those primary pages outrank any secondhand summary.

Billing guidance changes, and usually nobody tells you it changed. The durable habit isn't memorizing the current answer, it's knowing which shelf the answer is on and going back to that shelf each time:

• The CPT manual itself, for the code descriptors and their time ranges.
• APA Services' Psychotherapy Services FAQ, which walks the psychotherapy codes, session length, and documentation in plain language.
• APA Services' psychotherapy codes page, for the full descriptor set, crisis codes included.
• Your MAC's Local Coverage Determinations, for Medicare work.
• Each commercial plan's published coverage policies.

And a rule of thumb for everything else you'll hear in consultation groups and comment threads. If a billing rule can't be traced to the CPT manual, an APA Services page, or a payer's own published policy, don't act on it.

Then run the session the treatment calls for, and note when it started and when it stopped. The code follows from the time range, and the policy pages are an occasional read, not a weekly one. For what it's worth, the billing side of ERP turns out smaller than it feels from inside the open note at minute 68. The treatment was always the part worth your attention.