Question CPTs 99601/99602 - Questions

[nicolecdemarco305@gmail.com]

Any insight on the below questions would be greatly appreciated


1. 99601 is a primary code defined as "Home infusion/specialty drug administration, per visit (up to 2 hours);". Is 1 unit of 99601 equal to 2 hours?

2. 99602 is an add-on code to 99601 that is defined as "Home infusion/specialty drug administration, per visit (up to 2 hours); each additional hour (List separately in addition to code for primary procedure)". Is 1 unit of 99602 equal to 1 OR 2 hours?

3. Per the CMS Medicaid MUE Table for Q1 2026, 99601 has an MUE of 4 with the rationale "Clinical: Medicaid Data". Does this rationale mean the MUE is based in hours or units? If units, how would it be possible to have 4 units of the primary code 99601 billed on a single DOS when the code is listed as "up to 2 hours"?

4. Per the CMS Medicaid MUE Table for Q1 2026, 99602 has an MUE of 2 with the rationale "Clinical: Medicaid Data". Does this rationale mean the MUE is based in hours or units? If units, how would it be possible to only allow 2 units of the add-on code 99602 billed on a single DOS when the code is listed as "each additional hour"?


Issue we are having is that a member could receive several hours of home infusion and we need to understand how coders are expected to bill and get reimbursed for the services by Medicaid.

 

[sls314]

Any insight on the below questions would be greatly appreciated


1. 99601 is a primary code defined as "Home infusion/specialty drug administration, per visit (up to 2 hours);". Is 1 unit of 99601 equal to 2 hours?

2. 99602 is an add-on code to 99601 that is defined as "Home infusion/specialty drug administration, per visit (up to 2 hours); each additional hour (List separately in addition to code for primary procedure)". Is 1 unit of 99602 equal to 1 OR 2 hours?

3. Per the CMS Medicaid MUE Table for Q1 2026, 99601 has an MUE of 4 with the rationale "Clinical: Medicaid Data". Does this rationale mean the MUE is based in hours or units? If units, how would it be possible to have 4 units of the primary code 99601 billed on a single DOS when the code is listed as "up to 2 hours"?

4. Per the CMS Medicaid MUE Table for Q1 2026, 99602 has an MUE of 2 with the rationale "Clinical: Medicaid Data". Does this rationale mean the MUE is based in hours or units? If units, how would it be possible to only allow 2 units of the add-on code 99602 billed on a single DOS when the code is listed as "each additional hour"?


Issue we are having is that a member could receive several hours of home infusion and we need to understand how coders are expected to bill and get reimbursed for the services by Medicaid.

This MLN booklet explains how to use the Medicaid NCCI Tools: https://www.cms.gov/files/document/...onal-correct-coding-initiative-ncci-tools.pdf

MUE tables are based on units. (Image below is from the MLN booklet linked above)



MUE Rationale that is based on "Clinical: Medicaid Data" uses benchmarks based on historical Medicaid claims data to determine a reasonable MUE. Clinical benchmarking MUEs could be appealed with documentation. (As opposed to the MUE Rationale "Anatomical Considerations", for example. Those are a hard MUE limit per day based on anatomy and not appealable. For example, people only have one nose, so there's an MUE of 1 based on anatomical considerations for 92512.)


This link on the CMS website has all the FAQ and guidance for Medicaid NCCI: https://www.cms.gov/medicare/coding-billing/ncci-medicaid/medicaid-ncci-faq-library

Home infusion is not my area of expertise, but I think there are some logical conclusions to be drawn based on the CPT code descriptions and the MUE table:

99601 is PER VISIT (up to 2 hours). If the MUE is 4, then there must be circumstances where a patient might have multiple visits in a day, but Medicaid NCCI thinks that more than 4 visits in a day are medically unlikely. Based on clinical benchmarking data.

99602 is the add on for each additional hour. If the MUE is 2, then Medicaid NCCI has determined that more than 2 additional hours in a day is medically unlikely. Based on clinical benchmarking data.

So, basically, they're saying that a visit longer than 4 hours is medically unlikely. 2 hours (1 unit of 99601 for that visit) + 2 hours (2 units of 99602) = 4 hours.

Remember that these have an MUE rationale of "Clinical: Medicaid Data" so if a patient had a medically necessary home infusion visit lasting longer than 4 hours, you could appeal the MUE denial with documentation proving medical necessity.

The links I provided above to the Medicaid NCCI policy manuals and guidelines should have instructions on how to appeal the MUE denials.