Intensive Outpatient Program (IOP) Billing: Codes, Authorizations and Common Denials

Intensive outpatient programs are billed differently by different payers: many commercial plans pay a per diem using S9480 (mental health IOP) or H0015 (substance use IOP), facility-based programs often bill on the UB-04 with revenue codes 0905 or 0906, and some payers want each individual and group session billed separately. Almost every payer requires prior authorization, attendance records for each day, and regular clinical updates to keep the authorization going.

IOP billing mistakes are expensive because they repeat: a wrong code or missing authorization affects every day of every patient in the program.

Common IOP codes

Code	What it is	Where it is used
S9480	Intensive outpatient psychiatric services, per diem	Many commercial payers, for mental health IOP
H0015	Alcohol and/or drug intensive outpatient treatment	Commercial and Medicaid plans, for substance use IOP
Revenue code 0905	Intensive outpatient services, psychiatric	Facility claims on the UB-04
Revenue code 0906	Intensive outpatient services, chemical dependency	Facility claims on the UB-04
90853, 90832–90837, 90791	Group, individual and evaluation services	Payers that pay per service instead of per diem

Which one applies depends on your contract. A per diem contract pays one rate per day of attendance that meets the program’s minimum hours; a per-service contract pays each group and individual session separately. Check the contract before building your billing workflow.

Professional or facility claim?

• Professional claims (CMS-1500 / 837P) are used by programs billed as a practice or clinic, with HCPCS or CPT codes.
• Facility claims (UB-04 / 837I) are used by licensed facilities and hospital outpatient programs, with revenue codes plus HCPCS where the payer requires them.

Using the wrong claim type is one of the most common reasons new IOPs are denied at the start. Our guide to professional vs institutional claims explains the difference.

Authorizations

• Request authorization before the patient’s first day, with the level-of-care criteria the payer uses.
• Authorizations usually cover a set number of days. Track days used against days approved for every patient.
• Send clinical updates (concurrent review) before the authorization runs out, not after.
• When a patient steps down to regular outpatient care, a new authorization or different codes may apply.

Documentation for every day billed

• Attendance with start and stop times, showing the program’s minimum hours were met
• The groups and individual sessions provided that day
• Progress toward the individualized treatment plan
• Signed treatment plan and regular updates

Days that do not meet the minimum hours usually cannot be billed as a program day.

Medicare IOP

Since January 1, 2024, Medicare covers intensive outpatient services in hospital outpatient departments, community mental health centers, federally qualified health centers, rural health clinics and opioid treatment programs, with specific requirements for physician certification and treatment plans. Private practice IOPs are not among the covered settings, although individual services may still be billable under regular outpatient rules.

Common IOP denials

Denial	Cause	Fix
Authorization exceeded	Days billed beyond the approved number	Daily tracking; concurrent review before the last approved day
Wrong code or claim type	Per diem billed where the contract pays per service, or the reverse	Build billing from the contract
Minimum hours not met	Attendance records show a short day	Bill according to the payer’s rules for partial days
Level of care not supported	Clinical updates do not show why IOP is still needed	Stronger concurrent review documentation

We bill IOPs and group programs for mental health and substance use. See substance use and IOP billing and group practice billing.

Frequently asked questions