Bonnie Kirschenbaum, MS, FASHP
“Reimbursement Matters” is a tool for maintaining your health system’s fiscal health. Please email the author at with suggestions on reimbursement issues that you would like to see covered.

Using incorrect billing units for drugs in payment claims to Medicare and Medicaid has escalated to the point that this is one of the key findings during examinations of our billing systems by recovery audit contractors (RACs). So here are a few tips to stay clear of trouble.

First, know that very expensive medications are a natural target for RAC audits. There have been so many issues with inappropriate and incorrect billing of rituximab and bevacizumab, for example, that in a recent publication of Medicare Learning Network’s MLN Matters (​19oAlIR), these two drugs were used as examples of exactly how to use billing units correctly (Table). As the publication details, there are several key issues to keep in mind.

As a starting point, the article noted, be sure to focus on the overall goal—to convert the actual dose of a drug ordered for the patient into the number of billing units to be submitted for payment to Medicare or Medicaid. During that process, you’ll need to ensure that you’re using the assigned billing unit for the product. Sounds simple enough, right? After all, it’s just basic arithmetic! So how and where do things go awry? Here are a few potential source for miscalculations:

Your hospital’s billing department is doing the calculations manually, either because there is no computer system in the outpatient areas or, for whatever reason, the system can’t be programmed to do the calculations. Or the person(s) doing the calculations are not skilled in performing the conversions.

Rather than using automated “crosswalk” software to do these calculations before the information is sent to the billing system, order entry is being manipulated to accommodate billing units. These order-entry manipulations can lead to medication errors and other problems if the billing units rather than the dose appear on any clinical documents.

Multiple entries for the same product are being made in the charge description master and/or drug dictionary or pharmacy drug master, or there is a mismatch between the two, as well as inconsistencies in how billing units are assigned to each of these products.

There are multiple ways of acquiring the drug (automated cabinets, infusion center pharmacy, etc.), as well as different computer systems in outpatient clinics vs. the emergency room vs. pharmacy department, etc., resulting in a potential mismatch in the description of a product and its corresponding billing unit.

There’s no defined strategy for timely input of codes changes, billing unit changes or other updates.

e-Library a Crucial Tool

To avoid these types of problems, build an e-library for your pharmacy department that contains timely information on ever-changing reimbursement codes and policies. This will help you untangle the complex web of billing for medications. Here’s a list of tips and resources that you can use to build your e-library:

  1. Know your local Medicare Part A or Part B Administrative Contractor (A/B MAC) and how to contact them. There are subtle differences between carriers, so don’t depend on a recommendation from a colleague covered by a different MAC. Toll-free MAC numbers can be found at
  2. Know where to find the list of medications that have National Coverage Determinations (NCDs) and what these are. Use the link at For example, the NCD for bevacizumab is Document ID: 110.17. A search can be done by drug name or document number. For regional variations in payment policies, known as local coverage determinations (LCDs), check your MAC’s website.
  3. Look at the long description in Healthcare Common Procedure Coding System (HCPCS) tables to be clear about how to describe a product; the truncated short description may not be sufficient. Find the alphanumeric HCPCS code listings at
  4. Know what the reimbursement rates for the product are going to be and confirm that the billing units you’re using are correct. Use the Medicare Part B Drug Average Sales Price tables that are updated quarterly. There are three tables with each update, one of which lists all the NDC numbers associated with a particular HCPCS code as well as the maximum number of billing units for that product. Visit
  5. Past issues of MLN Matters should occupy an important place in your e-library, in part because CMS payment decisions may continue for several years and just be updated for reference purposes. If you missed any of the MLN Matters articles as of June 2007, search the archives at For some illustrative examples, check out updates for colorectal cancer chemotherapy at; updates for rituximab and carboplatin are at
  6. Get started or refresh your understanding of reimbursement with Medicare Reference Manuals: and

Someone on your staff may already be on the distribution list for these materials. But, who is that mystery person and does that information get to you in a timely fashion? Since it’s your pharmacy budget that’s taking the hit for mistakes that are made, be proactive, get on the distribution mailing lists and have information sent to you directly!

Table. Key Points To Remember When Billing For Rituximab and Bevacizumab
  • J9310 is defined in the HCPCS manual as: Injection, rituximab, 100 mg
  • One (1) unit represents 100 mg of rituximab ordered/administered per patient
  • Rituximab should be billed based on units, not the total number of mg
    • For example, if the quantity administered is 200 mg and the description of the drug code is 100 mg, the units billed should be two (2).
  • C9257 is defined in the HCPCS manual as: Injection, bevacizumab, 0.25 mg
  • J9035 is defined in the HCPCS manual as: Injection, bevacizumab, 10 mg
  • One (1) unit represents 10 mg (J9035) or 0.25 mg (C9257) of bevacizumab ordered/administered per patient.
  • Bevacizumab should be billed based on units, not the total number of mg.
    • For example, if the quantity administered is 300 mg and the description of the drug code is 10 mg, the units billed should be thirty (30).
Source: MLN Matters SE1316. HCPCS, Healthcare Common Procedure Coding System