Why this matters
Compare rates using the same unit
Rate Compass brings together negotiated rates that may represent different units and scopes of care. Two dollar amounts should not be compared until you understand what each one purchases.
A per diem rate is often an all-inclusive daily payment used for higher levels of care such as ASAM levels of care, mental health residential treatment, partial hospitalization programs (PHP), and intensive outpatient programs (IOP). In these settings, the per diem typically bundles a defined set of facility, clinical, and program services into a single daily rate. However, the exact services included — and the requirements for billing a qualifying day — vary by payer and contract.
A per diem and a service-based rate answer different questions.
The two common payment units
Per diem
A per-diem rate is the negotiated amount for a qualifying day of care. It may bundle a defined set of facility and program services, but the services included — and the requirements for billing the day — vary by payer and contract.
For example, a $950 per-diem rate represents $950 for a qualifying day under that payment arrangement and often might include pharmacy, labs, and physician encounters in a single bundled rate. However, without the underlying contract detail we are not able to know definitively if the per diem allows other services to be billed alongside the negotiated rate for the same day.
Service or session-based
A service-based rate is tied to a specific procedure and billing unit. For example, Current Procedural Terminology (CPT) code 90834 describes 45 minutes of psychotherapy. A negotiated rate of $185 associated with 90834 represents that coded psychotherapy service.
It is not necessarily the total cost of the visit. Other services may be billed separately during the same encounter, subject to the payer contract and applicable claim rules.
What determines the payment unit
The payment unit is driven primarily by the care setting, code definition, and negotiated arrangement — not by the diagnosis or code family alone.
How the code types fit
CPT codes describe medical procedures and services and are maintained by the American Medical Association. Many outpatient behavioral-health CPT codes describe a discrete or timed service, but the CPT code description alone does not determine how a commercial payer will reimburse it, however, they often will follow the Medicare payment structure and guidelines.
HCPCS Level II codes often describe a broad range of bundled services, supplies, and programs and are managed by CMS. Depending on the code and contract, the billing unit may be a day, session, timed increment, week, month, or another unit.
Revenue codes identify the type of accommodation or ancillary service reported on an institutional claim. They may be associated with days, visits, treatments, tests, or other units.
Comparing rates in Rate Compass
Before comparing two rates, confirm:
- Unit: Is each rate per day, per service, per session, or another unit?
- Setting: Are the rates for comparable levels of care and billing settings?
For example, a $950 per-diem rate and a $185 psychotherapy rate are not directly comparable. Creating a daily estimate from service-based rates requires assumptions about service volume and separately billable care. Any resulting calculation should be clearly labeled as an estimate.
In Rate Compass
The currently available Inpatient, Residential, PHP, and IOP distributions, carrier statistics, and Top 20 lists reflect rates identified by Rate Compass as per diem.
The Outpatient page for SUD and the MH CPT code search displays rates based on encounters.