Key takeaways
- Most of an oncology practice's revenue sits in drugs, so drug units, NDCs and waste modifiers matter more than any other billing step. Medicare pays most Part B drugs at average sales price plus 6% (CMS).
- Since July 1, 2023, Medicare requires the JW modifier for discarded drug from single-dose containers and JZ when nothing is discarded; claims without either can be returned.
- Infusion administration codes follow a hierarchy (chemotherapy first, then other infusions, then pushes and hydration), and getting the initial service wrong changes payment on every line.
- Prior authorization runs per regimen and per drug, and payers increasingly require a preferred biosimilar first.
- Ask every oncology billing company the same 10 questions, test them on the same de-identified claims, and score them side by side.
What makes oncology billing different
A billing company that handles primary care well can still lose large sums on a single oncology claim. These are the areas where medical oncology billing experience shows:
- Drug units and NDCs. Each HCPCS drug code has its own billing unit (1 mg, 10 mg, 0.1 mg and so on). Units have to be converted from the administered dose, and many payers require the NDC and its quantity on the claim.
- JW and JZ modifiers. Discarded drug from a single-dose vial is billed on its own line with JW; when nothing is discarded, the drug line carries JZ. See our guide to JW and JZ modifiers.
- Infusion hierarchy. Chemotherapy administration (96413, 96415, 96417), therapeutic infusions (96365 to 96368), pushes and hydration (96360, 96361) are reported in a set order, with one initial service per encounter.
- Authorizations per regimen. A new line of therapy, a dose change or a switch to a biosimilar can each need a new approval. Treating without one is the most expensive denial in oncology.
- Site of service. Office-based infusion, hospital outpatient departments and ambulatory infusion centers are billed differently.
- Clinical trials, radiopharmaceuticals and patient assistance. Trial claims need the right modifiers and condition codes; radioligand therapies have their own codes and documentation; and copay assistance programs need tracking so patient balances are correct.
Signs your oncology billing needs a change
- Drug claims paid below the published rate, or underpayments nobody checks against the payer contract.
- Denials for "no authorization" after treatment has started.
- Waste modifiers missing or used inconsistently.
- Days in AR rising on high-dollar claims. Our days in AR guide shows the formula.
- Coders who are not trained on oncology regimens and drug units.
10 questions to ask an oncology billing company
Ask every company on your shortlist the same questions and record the answers. An oncology specialist answers with examples from regimens and drug claims.
- Which oncology practices do you bill for today? Medical oncology, hematology, radiation oncology and infusion centers each work differently. Ask for a reference that matches your setting.
- How do you check drug units and NDCs before a claim goes out? Look for a unit conversion check against the administered dose and the vial size, every time.
- How do you handle JW and JZ? Ask them to walk you through a claim with discarded drug and one without.
- How do you code infusion administration? Ask how they choose the initial service and how they use start and stop times from the infusion record.
- Who owns prior authorization, and how is it tracked? Ask how they track approvals per regimen, dose change and biosimilar switch, and what happens when an approval is about to expire.
- How do you find underpayments on drug claims? They should compare payments with your contracts and with Medicare's quarterly ASP payment limits, and dispute short payments.
- Which oncology EHRs do you work in? OncoEMR, iKnowMed, ARIA, MOSAIQ and others have their own charge capture workflows. Working inside your system keeps your data with you.
- What does the percentage cover, and what is extra? Get included and excluded services in writing. Authorization and patient assistance tracking are often quoted separately.
- What will we see each month? At minimum: collections, AR aging, denial rate by reason, drug underpayments found and recovered, and authorization status.
- Who owns the data, and what happens if we leave? Payer accounts should stay in your practice name, payments should go to your bank account, and open AR should be handed back on a written timeline.
Worked example: how one drug-unit error changes a claim
A patient receives 380 mg of bevacizumab (HCPCS J9035, billed per 10 mg). The practice opens four 100 mg single-dose vials, so 20 mg is discarded.
| Line | Correct billing | Common error |
|---|---|---|
| Drug administered | J9035 × 38 units (380 mg ÷ 10 mg) | J9035 × 4 units (number of vials) |
| Drug discarded | J9035-JW × 2 units (20 mg ÷ 10 mg), on its own line | Not billed, or added to the administered line |
| Result | 40 units billed, waste documented | About one tenth of the drug billed; waste unrecorded |
The same check applies to every drug on every claim. Ask each company to price this example on your own payer mix and to explain how their review would have caught the error.
How oncology billing companies charge
Most charge a percentage of net collections; some charge per claim. Because drug payments make oncology collections large, a small difference in the percentage is real money, but so is a missed underpayment. Compare the total cost for the same scope and ask what is quoted separately. If you are weighing outsourcing against an in-house team, our in-house vs outsourced billing cost calculator puts both on one page.
Scorecard for comparing two or three companies
Score each company from 1 to 5 on each line, using their written answers and a review of the same 20 de-identified claims.
| What to score | What a 5 looks like |
|---|---|
| Oncology experience | Current oncology clients and a reference in your setting |
| Drug units, NDCs and waste | A pre-bill unit check on every drug line |
| Infusion coding | Initial service and hierarchy taken from documented times |
| Authorizations | Tracked per regimen, with alerts before expiry |
| Underpayments | Payments checked against contracts and ASP limits, with disputes filed |
| Reporting | Monthly KPIs plus claim-level access in your own EHR |
| Price clarity | One written list of what the rate includes and excludes |
| Exit terms | You own the data and payer accounts, with open AR handed back on a written timeline |
Red flags
- No current oncology clients, or no references in your setting.
- Drug units "taken from the EHR" with no review.
- No plan for authorizations or underpayments.
- A fee based on charges instead of collections.
- Payments deposited into an account you do not control.
- A long contract with no exit plan or data return.
What to check in the contract
- A business associate agreement under HIPAA, and how patient data is accessed.
- Term, minimums and notice needed to end the agreement.
- Who owns the data and payer accounts, and how records come back.
- How open AR is worked after termination.
- The list of included and excluded services, including prior authorization.
- Reporting you receive and how often.
Where PhysiAssist fits
PhysiAssist bills for medical oncology and hematology practices and cancer centers, including infusion and radioligand therapy claims. Certified coders check drug units, NDCs, JW and JZ and infusion hierarchy before claims go out, and we work inside OncoEMR, iKnowMed, ARIA, MOSAIQ and other oncology systems. Our RegimenIQ software shows drug cost, reimbursement and margin for each regimen before treatment starts. PhysiAssist charges 2.8% to 5% of net collections, with no setup fees or minimums; see pricing and our oncology billing services. We would rather you compare us with others using the questions above than take our word for it.
Frequently asked questions
What does an oncology billing company do?
It checks eligibility and authorizations, codes drug and infusion claims, submits them, posts payments, finds underpayments, works denials and follows up on unpaid claims for a cancer practice or infusion center.
How much does an oncology billing company cost?
Most charge a percentage of net collections. PhysiAssist charges 2.8% to 5% of net collections, with no setup fees or minimums. Compare the total cost for the same scope, including prior authorization.
How does Medicare pay for oncology drugs in the office?
Most separately payable Part B drugs are paid at average sales price plus 6%, using payment limits CMS publishes every quarter. Discarded drug from single-dose containers is reported with JW, and JZ is used when nothing is discarded.
Why do oncology claims get denied after treatment?
The most common causes are missing or expired authorization for the regimen, drug units that do not match the dose, missing NDCs, wrong infusion hierarchy and diagnosis codes that do not support the drug under the payer's policy.
Is infusion center billing different from oncology practice billing?
Yes. Ambulatory infusion centers often bill many specialties' drugs, rely heavily on authorizations and site-of-care rules, and may bill under different arrangements than a physician office. Ask the billing company which setting it works in today.
Sources
- CMS, Medicare Part B drug average sales price (payment limit of ASP plus 6 percent, published quarterly).
- American Academy of Family Physicians, Medicare modifier JZ (JW and JZ required from July 1, 2023; claims without them may be returned from October 1, 2023).
- CMS HCPCS Level II: J9035, injection, bevacizumab, 10 mg.