Chemotherapy administration time incorrect (Updated for 2026)

Common Causes for ON20

Denials with code ON20 typically happen for the following specific reasons:

• Billing for an additional hour of infusion (e.g., CPT 96415) when the documented duration did not exceed the initial hour by the required 31-minute threshold.
• Missing or incomplete documentation of infusion start and stop times within the patient's medical record or medication administration record (MAR).
• Billing an initial chemotherapy infusion code (e.g., 96413) for an administration that lasted 15 minutes or less, which according to CPT guidelines must be coded as an intravenous push (96409).
• Overlapping infusion times documented for concurrent or sequential administrations without clear clinical justification or proper modifier usage.

How to Prevent ON20 Denials

To avoid receiving this denial in the future, implement these specific checks:

• Mandate the use of electronic flowsheets with hard stops requiring clinical staff to record precise start and stop times for all chemotherapy administrations.
• Implement automated billing system rules that calculate elapsed infusion time and auto-select the correct CPT code hierarchy based on AMA guidelines.
• Conduct regular education sessions for oncology nursing and coding staff on the CPT 'time rules,' focusing on the 15-minute push threshold and the 31-minute additional hour threshold.
• Perform pre-bill audits on oncology claims to cross-reference the medication administration log against the selected billing codes.

Appeal Letter Template for ON20

If you believe this claim was denied incorrectly, you can use the following template to submit an appeal.

[Your Practice Header]
[Date]

[Payer Name]
[Appeals Department Address]

RE: Appeal for Claim [Claim Number]
Patient: [Patient Name]
ID: [Patient ID]
Date of Service: [Date]
Denial Code: ON20 - Chemotherapy administration time incorrect

Dear Appeals Department,

I am writing to appeal the denial of the above-referenced claim, which was denied with code ON20: "Chemotherapy administration time incorrect".

We are writing to appeal the denial of code ON20 for chemotherapy administration, as the clinical documentation fully supports the billed services and duration. In accordance with AMA CPT guidelines, code 96413 is designated for the initial chemotherapy infusion up to one hour, and add-on code 96415 is utilized for each additional hour of infusion time when the duration exceeds the initial hour by more than 30 minutes. The enclosed Medication Administration Record (MAR) clearly documents the exact infusion start time of [Insert Start Time] and stop time of [Insert Stop Time], establishing a total infusion time of [Insert Total Time] minutes. This precisely matches the units and codes submitted on the claim. Because our documentation meets all CMS and AMA CPT billing criteria, we respectfully request that this denial be overturned and the claim be processed for immediate payment.

Attached please find:
1. A copy of the original claim.
2. The relevant medical records supporting the service.
3. [Any other supporting documents].

We respectfully request that you reprocess this claim for payment.

Sincerely,

[Your Name]
[Title]
[Practice Name]