What are the billing rules for C161A?

You must report your findings, opinions or recommendations in writing to the patient's primary care physician, or it is paid as a lesser assessment (GP24). Limited to 4 per patient per physician per 12 months; excess is paid as a lesser assessment (GP24). Any combination of medical specific assessments and complex medical specific re-assessments is also limited to 4 per patient per physician per 12 months (GP23–GP24).

Why is C161A rejected?

AT2: Billed by telephone (K301A). This code is on Appendix J's video-only list, so it must be done by video and claimed with K300A (AJ2).

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Billing code

C161A — Nephrology complex medical specific re-assessment – hospital in-patient

Q: What is OHIP billing code C161A?

Nephrology re-assessment of a hospital in-patient whose condition is complex, obscure or serious, with a written report to the primary care physician.

Complex nephrology in-patient re-assessment

Bill C161 when a nephrologist re-assesses an in-patient because the condition is complex, obscure or serious, with a written report.

Watch for: Report in writing to the primary care physician, or it pays as a lesser assessment; limit 4 per patient per 12 months.

Provider	Specialist	Assistant	Anaesthetist	Non-anaesthetist
$0.00	$83.40	$0.00	$0.00	$0.00

Code: C161A
Description: Nephrology complex medical specific re-assessment – hospital in-patient
FHO+ basket: Not in the FHO+ base rate basket (Schedule 2 or 2B).
Effective date: Apr 1, 2026
Termination date: No end date

Explanation

Updated October 26, 2026

Nephrology re-assessment of a hospital in-patient whose condition is complex, obscure or serious, with a written report to the primary care physician.

What it covers

A complex medical specific re-assessment is a re-assessment because of the complexity, obscurity or seriousness of the patient's condition. It includes everything in a medical specific re-assessment (a full relevant history and exam of one or more systems) (GP23–GP24).

C161 is the non-emergency hospital in-patient version; the office version is A161 (A136–A137).

Billing rules

You must report your findings, opinions or recommendations in writing to the patient's primary care physician, or it is paid as a lesser assessment (GP24).
Limited to 4 per patient per physician per 12 months; excess is paid as a lesser assessment (GP24).
Any combination of medical specific assessments and complex medical specific re-assessments is also limited to 4 per patient per physician per 12 months (GP23–GP24).
Seeing patients in the ED or out-patient department while not on ED duty uses the A-prefix General Listings, not C-codes (A130, A137).
For chronic dialysis patients, admission assessments and subsequent visits to acute care in-patients for complications of dialysis, chronic renal disease or intercurrent illness are not included in the dialysis team fee and are billed separately (J39).
By video only, and for in-patients or LTC residents only when you are not the MRP, no local physician with the expertise is available (documented by the referrer), and the referrer saw the patient in person within the prior 30 days (AJ2, A69).

Common rejections

AT2: Billed by telephone (K301A). This code is on Appendix J's video-only list, so it must be done by video and claimed with K300A (AJ2).

Related codes: A161, C163, C164, C165, C162

Source: Schedule of Benefits (July 1, 2026), Consultations and Visits, Nephrology (16), page A137; rules GP23–GP24.

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