Outpatient parenteral antimicrobial therapy (OPAT) and other infusion services generate significant revenue for infectious disease practices — when they are billed completely. CPT codes 96365 through 96368 cover intravenous infusion for therapy and administration. Additional hours require add-on codes. Concurrent infusions require separate billing. Pump supplies, drug units, and nursing time may all be separately billable depending on the payer and the setting.

We regularly find ID practices billing only the primary infusion code while leaving add-on charges, concurrent administration codes, and drug units completely uncaptured. On a high-volume infusion schedule, those missed charges can represent tens of thousands of dollars per month.

Many infectious disease specialists are hospital-based consultants. Billing inpatient and outpatient consultations correctly especially after CMS eliminated consult codes for Medicare in 2010 and required the use of new and established patient E/M codes instead remains one of the most persistently incorrect billing areas in ID. Referrals from another physician need specific documentation to support the visit level. Split/shared visits in teaching hospitals require clear documentation of physician work. Missing any of these elements can trigger denials, downcoding, or compliance exposure.

Specialty medications, OPAT therapy, and certain diagnostic procedures all require prior authorization from most commercial payers and many Medicaid programs. One lapsed authorization, one incorrect procedure code on an auth request, or one failure to obtain auth renewal before an ongoing treatment cycle expires can result in a denied claim that is extremely difficult to recover after the fact. In an ID practice managing dozens of complex patients simultaneously, tracking every auth requirement manually is not sustainable.

Reimbursement for drugs administered in-office or in an infusion center depends entirely on accurate J-code assignment and correct unit billing. A single incorrect J-code or a failure to report the correct number of units for weight-based dosing can result in significant underpayment or outright denial. For high-cost drugs like intravenous immunoglobulin, antifungals, or newer antivirals, the reimbursement at stake on each claim is substantial.

Infectious disease telehealth expanded significantly post-pandemic, and CMS confirmed telehealth parity for office visit codes (99212–99215) in 2025. But capturing that revenue correctly requires the right modifiers (modifier 95 for synchronous audio-video visits, modifier 93 for audio-only when applicable), the correct place-of-service codes, and payer-specific telehealth policy compliance. Practices that apply blanket telehealth rules without checking payer-specific policies end up with denials that should have been easy revenue.

When a physician spends 45 minutes on a complex HIV patient managing drug interactions, resistance concerns, and co-morbid conditions, that visit should be billed at 99215. But if the note does not clearly establish total visit time, adequately document medical decision-making complexity, and capture all relevant diagnoses including comorbidities that affect management a payer auditor can legitimately downcode it to 99213 or 99214 and recover the difference. Documentation coaching is a revenue protection strategy, not just a compliance exercise.