IOP and PHP Billing: A Clear Guide for Behavioral Health Practices
IOP and PHP billing means submitting claims for intensive outpatient programs (IOP) and partial hospitalization programs (PHP), the two structured day-program levels between weekly therapy and inpatient care. Medicare pays for both, but each has its own hour threshold, certification rules and claim details. This guide walks psychotherapists and psychiatrists through what to check before a claim goes out.
Get a Free QuoteSchedule a ConsultationOn this page
Last reviewed: 10/10/26. Sources are listed at the bottom of this page.
What IOP and PHP billing covers
IOP and PHP billing starts with two organized, multi-hour treatment days that Medicare treats as different benefits.
A partial hospitalization program is intensive outpatient psychiatric care, including substance use disorder (SUD) services, delivered in programs that run less than 24 hours a day. An intensive outpatient program is a distinct, organized ambulatory program for acute mental illness, including SUD, that is less intense than PHP. Good IOP and PHP billing starts with knowing which of the two you are actually running.
Medicare added the IOP benefit for services on or after January 1, 2024, under section 4124 of the Consolidated Appropriations Act of 2023. The rules sit in CMS Transmittal 12425 and the CMS Medicare mental health booklet (checked 10/10/26).
| Item | PHP | IOP |
|---|---|---|
| Weekly hours | At least 20 hours per week | At least 9 hours per week |
| Patient risk | Discharged from inpatient care, or at reasonable risk of admission without PHP | Does not need inpatient-level care; no inpatient-risk test |
| Physician recertification | At least every 30 days | At least every 60 days |
| Hospital condition code | 41 | 92 |
| Where offered | Hospital outpatient departments and community mental health centers | Hospitals, critical access hospitals, community mental health centers, federally qualified health centers, rural health clinics and opioid treatment programs |
What is the difference between IOP and PHP?
PHP is the more intensive level. It requires a physician to certify at least 20 hours of treatment per week, and the patient would otherwise be at reasonable risk of inpatient care. IOP requires at least 9 hours per week for a patient who does not need 24-hour supervision. Your IOP and PHP billing rules follow from that split, so say which level each program is in every note and on every claim.
Why IOP and PHP billing trips practices up
Most denials in this area trace back to a mismatch. The program is labeled IOP in the chart but billed as PHP, or the weekly hours in the notes do not match the certification. Clean IOP and PHP billing needs the schedule, the certification and the claim to tell the same story. If you are still building the business side, the practice management guides and the MCM South resources library cover revenue and cash flow basics.
Medicare, Medicaid and private rules for IOP and PHP billing
Keep these three sets of rules apart. A Medicare rule is not a Medicaid rule, and neither is your commercial contract.
Medicare
Everything in the table above comes from Medicare manuals. Medicare covers PHP and IOP as separate benefit categories, and denials for benefit category are not appealable by the provider, while reasonable-and-necessary denials are. That matters for IOP and PHP billing because the fix is different for each. A benefit denial means the program did not fit the benefit. A necessity denial means your documentation did not prove the need.
Medicaid
Each state Medicaid program decides whether it covers IOP, PHP or both, which codes it accepts and which provider types may bill. Do not carry Medicare hour thresholds into a Medicaid claim. Read the state provider manual or bulletin for each state where you bill, and keep a separate note per state.
Private payers
Commercial plans set their own level-of-care definitions, authorization steps and code sets, usually in the provider contract or a medical policy. Many ask for prior authorization and concurrent review. Ask each plan how it labels IOP and PHP and which revenue codes and HCPCS codes it expects before you submit the first claim. Our private insurance guides and in-network versus out-of-network overview show where those differences usually start.
Who can furnish and bill IOP and PHP services
IOP and PHP billing is done by an enrolled provider type, not by an individual clinician acting alone.
For Medicare, PHP is a hospital outpatient department or community mental health center benefit. IOP can also be furnished by critical access hospitals, federally qualified health centers (FQHCs), rural health clinics (RHCs) and opioid treatment programs (OTPs). A solo practice that is none of these generally cannot bill Medicare for either program under its own number.
Inside a qualifying program, the CMS mental health booklet says physicians and several other practitioners can furnish services. A physician certifies the need and signs the plan of care. For IOP in an OTP, nurse practitioners, physician assistants, clinical psychologists, clinical social workers, mental health counselors and marriage and family therapists allowed by state law may certify and write the plan.
Individual billing rules for social workers, marriage and family therapists and counselors change inside these programs. The CMS booklet notes they are not paid under their own benefit categories for services to patients in a hospital outpatient or community mental health center PHP or IOP. Their work is paid through the program claim, which is why IOP and PHP billing looks different from regular outpatient billing. See our who we serve page for the practice types MCM South works with.
For FQHCs, CMS Transmittal 13506 (December 5, 2025) sets the 2026 IOP payment at $319.38 for three or fewer services in a day and $418.45 for four or more, paid as the lesser of charges or the rate. Those figures are for FQHCs only.
7 steps for clean IOP and PHP billing
Run these seven steps in order before the first claim of any new IOP and PHP billing workflow.
- Confirm the program type. Decide whether you are running PHP (20 hours) or IOP (9 hours) and write the weekly schedule down.
- Confirm your enrollment. Check that your provider type is allowed to furnish the benefit, and that your credentialing is complete with each payer.
- Get the physician certification. The physician certifies the weekly hours at admission and signs an individualized plan of care.
- Build the recertification calendar. Medicare asks for PHP recertification at least every 30 days and IOP at least every 60 days.
- Document every service. Progress notes describe each service, the patient response and how it ties to the treatment plan goals.
- Code the claim. Use the condition code, bill type, revenue code and procedure code each payer asks for (see the next section).
- Work the remittance. Read the electronic remittance advice for denial codes and match each one to the right appeal path.
Claim details that matter in IOP and PHP billing
These IOP and PHP billing items come from Medicare Part A guidance. Private plans and Medicaid may use different ones.
Hospital PHP claims use the bill types 131 through 134, with 131 for admit through discharge and 132 to 134 for interim claims, according to the Noridian PHP billing guide (checked 10/10/26). Hospitals report condition code 41 for PHP. CMS Transmittal 12425 added condition code 92 for IOP.
| Claim item | What Noridian lists | Note |
|---|---|---|
| Revenue codes | 0250, 043x, 0900, 0904, 0914, 0915, 0916, 0918, 0942 | Each service line needs one plus a procedure code |
| Individual psychotherapy | 90785, 90832, 90833, 90834, 90836, 90837, 90838, 90845, 90880 | Hospital procedure codes |
| Group and family therapy | G0410 or G0411; 90846 or 90847 | Group therapy is paid inside the IOP payment |
| Diagnostic and testing | 90791 or 90792; 96116 | Evaluation and psychiatric testing |
| Other program services | G0129 occupational therapy; G0176 activity therapy; G0177 education and training | Must be part of the plan of care |
Only certain codes are billable inside a PHP or IOP. The booklet points to the Medicare Claims Processing Manual, Chapter 4, sections 260 and 261, for the list, so read those sections before you build a charge master for IOP and PHP billing. The broader CPT code guide helps with code definitions. Off-campus hospital departments also report modifier PN or PO depending on their status.
Use the CMS-1500 guide for professional claims and the claims processing terms for the vocabulary. For program-level IOP and PHP billing at a private plan, the contract is the final word.
What to do Monday morning
Four jobs for your IOP and PHP billing, in this order.
- Write down which level of care each of your programs is for IOP and PHP billing purposes, and the weekly hours it actually delivers.
- Pull the last three months of IOP and PHP billing claims and check that the condition code and revenue code on each match the program type.
- List every patient whose physician recertification is coming up and put the date on the calendar.
- Read your latest denials against the claim denials and appeals guide and sort them into benefit denials and necessity denials.
Frequently asked questions
How many hours does Medicare require for IOP and PHP billing?
Medicare requires at least 9 hours per week of treatment for an intensive outpatient program and at least 20 hours per week for a partial hospitalization program. A physician certifies the hours, and the program must show them in the plan of care and notes.
How often must a physician recertify IOP and PHP patients?
Per the CMS materials checked 10/10/26, Medicare PHP recertification is needed at least every 30 days, and IOP recertification at least every 60 days. Providers may set shorter intervals. Confirm your payer's own interval before you build the calendar.
Can a solo therapist handle IOP and PHP billing for Medicare?
Not as a stand-alone program. Medicare pays PHP through hospital outpatient departments and community mental health centers, and IOP through a longer list of enrolled provider types. A private practice can furnish services inside a qualifying program, but the program submits the claim. That shapes IOP and PHP billing for every group.
Do Medicaid and private plans use the same IOP and PHP billing rules?
No. Each state Medicaid program and each commercial plan sets its own level-of-care definitions, authorization steps and codes. Treat the Medicare thresholds as a starting point for IOP and PHP billing, then check the payer's policy or contract for every program you bill.
Want someone to handle IOP and PHP billing follow-up every week?
Get a free, no-pressure consultation with a specialist who only works mental and behavioral health billing.
Get a Free QuoteSchedule a Consultation