Infectious disease billing
Infectious disease billing services
We handle billing for infectious disease physicians and practices, from inpatient consults and hospital follow-ups to outpatient infusion therapy and long-term HIV care. Claims go out within 24 hours of receiving charges, every denial is worked within 5 business days, and billing starts at 2.5% of collections.
- Inpatient consult coding by payer (consult codes vs initial hospital care)
- Infusion and drug billing with NDCs, units and waste modifiers
- HIV and chronic infection coding that follows ICD-10 rules
Why infectious disease billing is different
Why infectious disease billing is different
ID physicians split their time between the hospital and the clinic, and much of the revenue sits in consults, long hospital stays and expensive drugs. Each of those has its own rules.
Consults are billed differently by payer
Medicare does not pay the consultation codes (99242–99245 and 99252–99255). For Medicare, an inpatient consult is billed as initial hospital care. Some commercial plans still pay consult codes. We keep the rule for each payer.
Hospital follow-up and split visits
Daily subsequent hospital visits add up fast. When a physician and an NP or PA share a visit, Medicare split or shared rules and modifier FS decide who bills. Two ID clinicians seeing the same patient on the same day can also trigger duplicate denials.
OPAT and infusion drugs
Outpatient IV antibiotics are billed as an administration code plus the drug. The drug needs the right HCPCS code, units that match the dose, the NDC where required, and a JW or JZ modifier for single-dose vials under Medicare rules.
HIV and chronic infection coding
Diagnosis coding drives payment and risk scores. Under ICD-10 guidelines, a patient with a prior HIV-related illness keeps the B20 code rather than Z21. Hepatitis, long-term drug use and resistance codes need to be specific too.
Prolonged services
Complex cases often run past the time of the top E/M level. CPT uses 99417 for prolonged outpatient time, while Medicare uses its own G-code with a different time threshold. Billing the wrong one means a denial.
Specialty drug authorizations
Long-acting injectables, HIV medicines and some antibiotics often need prior authorization or must come through a specialty pharmacy. We check coverage before the drug is bought or given.
Common codes
Infectious disease codes we bill often
| Code(s) | What it is | What we watch for |
|---|---|---|
| 99221–99223 | Initial hospital inpatient or observation care | Used for Medicare inpatient consults; level supported by decision making or time |
| 99231–99233 | Subsequent hospital inpatient or observation care | One visit per specialty per day; split or shared visit rules |
| 99252–99255 | Inpatient consultation | Commercial payers only where the contract allows; not Medicare |
| 99202–99215 | Office and outpatient visits | New versus established status within the same specialty group |
| 99417 / G2212 | Prolonged outpatient services (CPT / Medicare) | Correct code and time threshold for the payer |
| 96365 / 96366 | IV infusion, first hour and each additional hour | Start and stop times documented; paired with the right drug line |
| J-codes (for example J3370, J0878) | Drugs such as vancomycin and daptomycin | Units match the dose; NDC; JW or JZ modifier for single-dose vials |
Codes and rules change. We check current CPT guidance and each payer’s policy before submission.
Common denials we prevent
ID denials we stop before they happen
We check for the usual infectious disease problems during coding review, so fewer claims come back.
- Consult codes sent to Medicare or to plans that no longer pay them
- Duplicate same-day hospital visits from two clinicians in the same specialty
- Drug lines with units that do not match the dose given, or a missing NDC
- Missing JW or JZ modifiers on single-dose vial drugs for Medicare
- Infusion time not documented, so the add-on hour is denied
- Nonspecific diagnosis codes, or Z21 used where B20 applies
- Long-acting injectables given before authorization or benefits were confirmed
What we handle
Everything between the visit and the payment
- Insurance eligibility and benefits checks, including drug coverage
- Charge entry and coding review of hospital, office, infusion and drug codes
- Claim submission within 24 hours of receiving charges
- Payment posting and ERA reconciliation
- Denial correction, resubmission and appeals within 5 business days
- A/R follow-up on unpaid and underpaid claims
- Credentialing and hospital-based payer enrollment for physicians, NPs and PAs
- Patient statements and balance tracking
- Monthly reports on collections, denials and A/R
Behavioral health is our core focus. We bill infectious disease and other specialties with the same team, the same promises and CPB-certified billers on the team.
Pricing
Clear pricing for infectious disease practices
Billing starts at 2.5% of collections, or a flat monthly fee. There is no setup fee and no long-term contract. Credentialing starts at $80 per payer, and 5 commercial payers are credentialed free with billing.
Common questions
How do you bill inpatient ID consults for Medicare patients?
As initial hospital care (99221–99223), not consult codes. Medicare stopped paying consultation codes in 2010. Some commercial plans still pay them, so we follow each payer’s current rule.
Can two infectious disease doctors bill for the same patient on the same day?
Usually only one subsequent hospital visit per specialty per day is paid when the physicians are in the same group. If both provide separate, needed services, documentation must show that. We review these cases before they go out.
Do you bill OPAT and infusion drugs?
Yes. We bill the administration codes and the drug line, with units matched to the dose, NDCs where the payer requires them and JW or JZ modifiers for single-dose vials under Medicare rules.
Which diagnosis code do you use for HIV?
It depends on the patient’s history. ICD-10 guidelines use Z21 for asymptomatic HIV infection and B20 once the patient has had an HIV-related condition, and B20 stays on from then on. We follow the documentation and current coding guidelines.
Do you bill prolonged services?
Yes, when the time is documented. Commercial payers usually follow CPT 99417, while Medicare uses its own G-code and time threshold. We apply the right one for each payer.
How much do infectious disease billing services cost?
Billing starts at 2.5% of collections, with flat monthly fees and dedicated billers also available. No setup fee and no long-term contract.
Guides from our team
Learn more before you decide
Top 10 Reasons for Medical Claim Denials (And How to Fix Them Fast)
The 10 most common reasons for medical claim denials, what each one costs your practice, and the exact fix for each. Plus a denial-prevention checklist.
Read the guide →Claim Denial Codes Explained: What CO-16, CO-50, CO-197, PR-1 and Others Mean and How to Fix Them
What common denial codes mean (CO-16, CO-18, CO-50, CO-97, CO-197, PR-1 and more) and how to fix each, for mental health and medical practices.
Read the guide →Medical Billing Services for Small Practices: Complete Guide to Maximizing Revenue
Explore medical billing services for small practices, from claim submission and payment posting to denial follow-up, with practical steps to improve revenue.
Read the guide →Find out what your claims are leaving on the table
Tell us about your practice. We will review 90 days of claims and show you what is recoverable, at no cost.
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