IRF Billing in 2026

The 60% Rule, the 3-Hour Therapy Standard and IRF-PAI Documentation

By Team Rcmaxis  ·  October 19, 2026  ·  12 min read

A May 2026 HHS OIG report put a number on something IRF billers have suspected for years: a 71% error rate on reviewed inpatient rehabilitation facility claims. That's down from the 84% error rate OIG found in its 2018 nationwide IRF audit, which sounds like progress until you remember that 71% still means most of the claims reviewed had a documentation or coverage problem. The specialty physician group AAPM&R has pushed back hard on how OIG extrapolated that rate into a dollar overpayment estimate, and the report itself found no evidence of fraud. But the underlying pattern, Medicare Administrative Contractors interpreting the same federal rules differently from one jurisdiction to the next, is exactly the kind of inconsistency that turns a clean-looking IRF stay into a denied claim months later.

IRF billing runs on three separate tests that all have to hold up at once: a facility-level population test, a daily therapy-intensity standard, and a stack of required documentation that has to exist in a specific form, created at specific points in the stay. Fail any one of the three and the entire claim, not just a piece of it, is treated as an error.

Here's how the 60% rule, the 3-hour rule and the IRF-PAI documentation actually work, and where OIG keeps finding the gaps.

The 60% Rule: A Facility-Level Test, Not a Per-Claim Test

Before an individual IRF claim is even in play, the facility itself has to keep qualifying for IRF PPS classification. Under 42 CFR 412.29(b)(2), at least 60% of a facility's total inpatient population during its compliance review period must require intensive inpatient rehabilitation for one or more of 13 specific qualifying conditions, stroke, spinal cord injury, amputation, major multiple trauma, and the rest of the list CMS maintains in regulation.

The facility's Medicare Administrative Contractor reviews this compliance, typically once a year at the start of the facility's cost reporting period, looking at the whole patient population over that period, not individual claims. A facility that falls below 60% doesn't just lose payment on the patients who didn't fit one of the 13 conditions; it risks its entire IRF classification, which reclassifies the whole facility's payment structure going forward.

The 3-Hour Rule: What Actually Counts and What Doesn't

The intensity-of-therapy standard that CMS generally expects an IRF patient to receive is at least 3 hours of therapy a day, at least 5 days a week. Only four therapy types count toward that total: physical therapy, occupational therapy, speech-language pathology, and prosthetics/orthotics training. Nursing time, physician visits and other services, however valuable clinically, don't count toward the 3-hour figure.

CMS has also been explicit that reviewers shouldn't deny a claim solely because the documented therapy time fell short of the 3-hour threshold. In 2018 guidance, CMS told auditors that medical necessity for inpatient rehabilitation has to be judged on the individual patient's case, and that missing the therapy-time standard isn't, by itself, grounds for denial if the rest of the record supports the need for an IRF-level stay. That guidance cuts both ways: it protects a clinically appropriate stay that happened to log 2 hours 50 minutes one day, but it also means your documentation of medical necessity has to stand on its own, not lean on the hours log as a substitute.

IRF-PAI Documentation: The Three Records OIG Keeps Flagging

Every OIG audit of IRF claims circles back to the same three pieces of required documentation, and when one is missing or thin, the whole claim's payment is treated as an error, not just discounted. A full pre-admission screening has to capture the patient's medical and functional status before admission. A post-admission rehabilitation physician evaluation has to be completed within the required timeframe after the patient arrives. And an individual overall plan of care, developed and signed by the rehabilitation physician, has to be in the chart, specific to that patient, not a generic template.

Single-hospital OIG audits show how expensive gaps in these three documents get. At Memorial University Medical Center in Georgia, OIG found errors on 23 of 30 audited IRF claims, largely because stays didn't meet Medicare's criteria for acute inpatient rehabilitation. At Mobile Infirmary Medical Center in Alabama, OIG estimated at least $340,125 in overpayments tied to claims that either didn't meet IRF criteria or didn't satisfy documentation requirements. At Rush University Medical Center in Chicago, OIG attributed $792,946 of its overpayment finding specifically to a failure to establish medical necessity for inpatient rehabilitation, a finding the hospital disputed.

Why MAC Interpretation Differences Make This Harder

The May 2026 OIG report's core finding is worth sitting with: unclear federal requirements have led different Medicare Administrative Contractors to interpret the same IRF documentation, coverage and billing rules differently. That means a stay that would pass review in one MAC's jurisdiction can fail in another's, even with identical clinical documentation, purely because of how that specific contractor reads the coverage criteria.

CMS's response to the report reportedly leaned toward the stakeholders' perspective that the rules themselves need clarifying, which is a slower fix than anything a single IRF can control. In the meantime, the practical move is to document to the strictest plausible reading of each requirement, pre-admission screening, physician evaluation timing, individualized plan of care, rather than to whatever standard your specific MAC has been accepting. A standard that passes a lenient reviewer today can still fail a four-year lookback review under a stricter one later.

Build the IRF Documentation Workflow

Treat the three required documents as gates, not paperwork. No patient should reach the therapy floor without a completed pre-admission screening in the chart, and no claim should go out the door without confirming the post-admission physician evaluation and the individualized plan of care are both signed and specific to that patient.

Run a monthly internal audit on a small claim sample, checking all three documents plus the therapy-minutes log, before a MAC or OIG does it for you. Track your facility's 60% rule compliance on the same monthly cadence, not just at the annual review point, so a declining trend gets caught with enough runway to fix.

• Gate admission on a complete pre-admission screening. No screening, no admission, no exceptions.
• Confirm post-admission physician evaluation timing. Track the clock from admission, not from when someone remembers to document it.
• Individualize every plan of care. A templated plan of care is one of the fastest ways to fail a medical-necessity review.
• Audit a claim sample monthly. Catch the gap OIG would find, before OIG finds it.

Our guide to LTACH billing covers the adjacent long-term acute care pathway many IRF patients are compared against, and our skilled nursing facility billing guide explains the lower-intensity alternative a MAC reviewer may ask why your patient didn't use instead.

Frequently Asked Questions About IRF Billing

What is the IRF 60% rule?

To be classified and paid under the IRF PPS, at least 60% of a facility's total inpatient population during its compliance review period must require intensive rehabilitation for one or more of 13 qualifying conditions listed in 42 CFR 412.29(b)(2). The facility's Medicare Administrative Contractor reviews compliance, generally once a year at the start of the facility's cost reporting period, and falling below 60% puts the facility's entire IRF classification at risk, not just the individual claims.

What is the IRF 3-hour rule?

The generally accepted standard for demonstrating the intensity of therapy an IRF patient needs is at least 3 hours of therapy a day, at least 5 days a week, counting only physical therapy, occupational therapy, speech-language pathology and prosthetics/orthotics training. CMS also allows an alternative of at least 15 hours of intensive rehabilitation therapy across a 7-day window starting at admission, and reviewers aren't supposed to deny a claim solely because it missed the time threshold if the medical record otherwise supports the need for inpatient rehabilitation.

What does the IRF-PAI documentation need to include?

OIG's recurring findings point to three documents every IRF stay needs: a pre-admission screening that captures the patient's full medical and functional status, a post-admission rehabilitation physician evaluation completed within the required window, and an individual overall plan of care developed and signed by the rehabilitation physician. Missing or incomplete versions of any of the three have been the basis for OIG overpayment findings at multiple hospitals.

What did the 2026 OIG report on inpatient rehabilitation facilities find?

A May 2026 HHS OIG report found that unclear Medicare requirements have led Medicare Administrative Contractors to interpret IRF documentation, coverage and billing rules differently from one jurisdiction to the next, and cited an updated claim error rate of 71%, down from an 84% error rate OIG found in a 2018 nationwide IRF audit. The physician specialty group AAPM&R, which isn't a neutral party, has disputed how that error rate was extrapolated into an overpayment estimate, and says the report found no evidence of fraud or quality-of-care problems.