OIG Audit Triggers in Medical Billing: The 2026 Work Plan Explained

Why the 2026 OIG Work Plan Demands Immediate Attention

The Office of Inspector General of the US Department of Health and Human Services publishes and continuously updates a Work Plan that identifies the programs, services, and billing patterns it intends to audit. The 2026 Work Plan is not a prediction of where enforcement might eventually focus. It is a real-time log of active and announced audit projects with specific project numbers, announcement dates, and targeted dollar amounts already identified. Practices that read it in April 2026 have a shorter window to correct vulnerabilities than practices that read it in January. By June 2026 several projects announced earlier in the year are already generating active documentation requests to providers.

The enforcement environment in 2026 is more data-driven and more coordinated across audit entities than any prior year. The OIG, Recovery Audit Contractors, Supplemental Medical Review Contractors, and Unified Program Integrity Contractors are sharing findings and coordinating targeting in ways that create compounding audit exposure for practices flagged in any one program. Among the billing patterns that consistently surface as high-risk across all of these programs, unlisted codes as a top audit trigger remain a persistent concern because they bypass automated adjudication, require manual pricing, and generate no data trail that allows payers to benchmark payments against industry norms.

The 2026 Work Plan Updates That Matter Most to Physician Practices

The OIG Work Plan receives additions and completions continuously throughout the year. The following are the highest-impact updates announced and completed through June 2026 that directly affect physician practice billing.

Chronic Care Management: Active Audit Through 2028

On March 16, 2026, the OIG formally announced an active audit of Medicare Part B payments for Chronic Care Management services at risk of noncompliance (Project Number OAS-26-09-007). This project is expected to run through fiscal year 2028, making it one of the longest sustained audit initiatives in recent OIG history.

The trigger for this audit is straightforward. Medicare Part B payments for CCM services increased substantially between calendar year 2019 and calendar year 2024. Prior OIG audit work and a prior $14.9 million Department of Justice settlement with a chronic disease management provider established that CCM billing errors are both prevalent and financially significant.

The 2026 audit focuses specifically on the multiple chronic conditions requirement. To bill CCM, the patient must have two or more chronic conditions that are expected to last at least 12 months or until the patient dies, and that place the patient at significant risk of death, acute exacerbation, decompensation, or functional decline. The OIG is reviewing whether practices are billing CCM for patients who do not meet these documented thresholds, and whether vendor-led CCM models include sufficient evidence of the billing practitioner’s clinical involvement in the patient record.

Practices billing CCM should audit their patient records immediately to verify that the multiple chronic condition requirement is documented with specificity, that the billing practitioner’s role and oversight are visible in the record, and that any vendor arrangements for CCM delivery include appropriate supervision documentation.

Modifier 25: Sustained Enforcement with Escalating Consequences

Modifier 25 enforcement continued to intensify throughout 2025 and into 2026 following the OIG’s audit finding that of 1.4 million E/M services billed with modifier 25 on the same day as intravitreal injections, 42 percent lacked sufficient documentation to support the modifier, putting $124 million in payments at risk for recoupment. The March 2026 OIG Work Plan update confirmed that modifier 25 enforcement activity remains active and is now coordinated with the Supplemental Medical Review Contractor’s nationwide medical review project on modifier 25 use.

The convergence of OIG audit findings and SMRC nationwide review means that modifier 25 scrutiny is now systematically applied across all specialties, not just ophthalmology. The enforcement pattern mirrors what the OIG and Department of Justice have already pursued in wound care, where Vohra Wound Physicians settled for $45 million to resolve false claims allegations related to overbilling for wound care services that included modifier 25 misuse.

Practices billing E/M services with modifier 25 on procedure days must be able to demonstrate in the clinical record that the E/M service was significant, separately identifiable, and required clinical decision-making above and beyond the pre-procedure assessment. The E/M service must be documented in a separately identifiable note that can stand alone from the procedure note.

Peripheral Vascular Procedures: $105 Million Identified and Referred

On May 5, 2026, the OIG completed and released its report on peripheral vascular procedures performed in office-based laboratories (OBLs): Utilization Trends and Medicare Part B Billing for Office-Based Peripheral Vascular Procedures Raise Questions About Program Integrity (Report OEI-01-24-00250). The findings are significant and the enforcement response is already underway.

Medicare paid physicians approximately $548 million for peripheral vascular procedures in OBL settings in 2023. The OIG determined that approximately 19 percent of those payments, representing $105 million, may have been for medically unnecessary procedures. The OIG identified 139 physicians across vascular surgery, cardiology, interventional cardiology, and interventional radiology whose billing patterns raised program integrity concerns. CMS concurred with the OIG’s recommendation to follow up directly with those identified physicians.

RAC contractors announced selective catheter placement as a new priority audit category within weeks of the OIG report release, creating the compounding exposure mentioned earlier. Practices in these specialties should expect documentation-focused reviews that look specifically for evidence that conservative treatment was attempted before intervention, that catheter selectivity and vessel treatment are supported in the operative record, and that medical necessity is documented at every step of multi-vessel procedures.

Neurostimulator Implantation: $636 Million Overpayment Finding

The OIG concluded in a completed 2026 audit report that Medicare overpaid $636 million for neurostimulator implantation surgeries. This finding built on prior OIG work that had already identified improper payments for outpatient neurostimulator claims. CMS currently requires prior authorization for outpatient neurostimulator implantation surgeries but not for inpatient cases. The 2026 finding targets the inpatient gap in oversight.

The March 2026 Work Plan update flagged ongoing vulnerabilities in high-cost surgical procedures including neurostimulators as a continuing priority area. Practices performing neurostimulator implantations in any setting should verify that documentation includes clear medical necessity support, evidence of failed conservative treatment consistent with specialty society guidelines, and that prior authorization was obtained for outpatient cases.

Medicare Advantage Risk Adjustment: V24 to V28 Transition Scrutiny

A January 2026 Work Plan item specifically targets trends, patterns, and key comparisons between the V24 and V28 risk adjustment models. CMS moved to the V28 HCC model in 2024, which reduced the number of payable diagnosis mappings and was projected to save $7.6 billion. The OIG is examining how coding patterns changed during the model transition and whether providers adjusted their HCC coding in ways that do not reflect clinical reality.

For physician practices, this means that documentation supporting HCC risk adjustment diagnoses for Medicare Advantage patients must be current, must reflect conditions that the physician actively managed during the encounter, and must not rely on historical diagnoses carried forward without clinical reassessment at the encounter.

Virtual Check-In and E-Visit Services: Completed Report, Active Risk

On April 23, 2026, the OIG completed its review of CMS safeguards for virtual check-in and e-visit services, finding that CMS could strengthen program safeguards to identify inappropriate payments. This completed report signals the beginning of targeted enforcement in telehealth-adjacent billing, particularly for practices that dramatically increased virtual check-in and e-visit billing volume after these codes became widely reimbursed during the COVID-19 public health emergency and maintained that volume without corresponding documentation improvement.

Home Health: Nationwide Compliance Audit Announced

On April 23, 2026, the OIG announced a nationwide Medicare compliance audit of home health claims billed with an institutional admission source. This announcement primarily affects home health agencies but has downstream implications for physician practices that certify home health services. Certifying physician documentation must support the homebound status and skilled care need for each certified patient.

How Audit Selection Has Changed in 2026

The shift from random sampling to predictive modeling for audit selection is now fully operational across all major audit contractor programs. Providers are flagged based on multivariate analysis that simultaneously considers billing frequency compared to specialty peers, procedure mix relative to diagnosis patterns, geographic outlier status, referral relationship patterns, prior audit history, and complaint history including whistleblower reports.

Practices with billing patterns that deviate significantly from specialty peers on any of the 2026 Work Plan priority items face a materially elevated probability of audit selection. The OIG has demonstrated through the peripheral vascular report that it is willing to compile and refer lists of specifically identified physicians to CMS and RAC contractors when pattern analysis identifies concerning billing. That means the audit risk in 2026 is not just that a claim gets selected for review. It is that a physician’s entire billing pattern in a targeted category becomes the subject of a coordinated multi-contractor review.

What Practices Must Do Right Now

Practices that bill any of the 2026 Work Plan priority categories should take three immediate steps.

The first step is a focused internal chart audit of the highest-risk category for that practice. Pull a sample of 20 to 30 claims from the past 12 months in the applicable category and evaluate them against the specific documentation criteria the OIG has articulated in its 2026 work plan announcements. This audit should be conducted under attorney-client privilege if there is any possibility that it will identify significant overpayments requiring repayment obligations.

The second step is comparing the practice’s billing frequency and procedure mix for the targeted categories against the CMS Physician Supplier Procedure Summary data for the same specialty and geographic area. Practices that are billing a targeted procedure at more than twice the specialty benchmark frequency need a documented clinical explanation for that outlier status before an auditor asks for one.

The third step is updating documentation templates and clinical note structures to explicitly capture the elements the OIG has identified as deficient in each target category. Understanding what payers actually look for in medical necessity documentation is essential for building templates that survive audit scrutiny. For CCM, that means templates that document both chronic conditions meeting the clinical threshold. For modifier 25, that means separate E/M note sections that can stand independently of procedure notes. For peripheral vascular procedures, that means operative records that document the conservative treatment history before intervention. These template changes take days to implement and protect years of future billing.

Conclusion

The 2026 OIG Work Plan is more specific, more data-driven, and more consequential than any prior year. Practices billing diagnostic imaging should also be aware of the CMS anti-markup rule when Medicare is the secondary payer — see our detailed guide on billing Medicare secondary for global imaging code 74181. Active audit projects targeting chronic care management through 2028, coordinated enforcement on modifier 25 across all specialties, a $105 million peripheral vascular finding with named physician referrals to CMS, and a $636 million neurostimulator overpayment conclusion all represent real and immediate audit exposure for affected practices. The practices best positioned in this environment are those that read the Work Plan, compare their own billing patterns against its priorities, conduct privileged internal audits of high-risk categories, and update their documentation templates before the ADR letters arrive.