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OHIP Billing Guide🩺 ServicePublished 2026
C645

C645 OHIP Billing Code: Understanding Thoracic Surgery Consultations

The C645 code covers consultations for general thoracic surgery in hospital in-patient settings under OHIP. This guide helps physicians navigate billing for this service.

For Ontario Physicians & Billing StaffOHIP Schedule of Benefits Reference100.15 CAD~3 min read

1What Is the C645 OHIP Code?

What is the C645 OHIP Billing Code?

The C645 billing code is used under the Ontario Health Insurance Plan (OHIP) for consultations provided by thoracic surgeons to hospital in-patients. This service involves assessing patients with complex thoracic conditions, such as empyema, persistent air leaks, or newly diagnosed lung cancer, to provide expert surgical opinions during hospital admissions.

Due to the specific nature of the C645 code, it's essential to understand it is meant for consultations after a formal written request from a referring healthcare provider. This ensures appropriate cases, involving significant consultation for conditions like those mentioned, are adequately billed for the specialized thoracic surgical assessment.

2Related Codes

CodeNameFrequencyDescription
A935A935 Special surgical consultationSubject to general frequency limitsSpecial surgical consultation in general thoracic surgery.
C935C935 Special surgical consultationSubject to general frequency limitsSpecial surgical consultation in general thoracic surgery.
A645A645 ConsultationSame eligibility as C645, but for out-patient settingsConsultation in General Thoracic Surgery for out-patient settings.
A646A646 Repeat consultationOne service per eligible visitRepeat consultation in General Thoracic Surgery.

3Eligibility Requirements

Eligibility Requirements for Billing C645

To be eligible for billing the C645 code:

  • The consultation must be requested in writing by a referring physician, nurse practitioner, or dental surgeon.
  • The request should identify the consultant's name or specialty, the referring provider's name and billing number, and the patient's details, including name and health number.
  • Consultations for the same patient by the same physician and for the same diagnosis are limited to one every two consecutive 12-month periods, unless the second service is warranted by an inpatient referral or emergency department condition occurring more than 12 but less than 24 months after the first consultation.
  • A consultation is required to include a documented, written report back to the referring party, detailing the findings and recommendations made.

4What Your Clinical Note Must Show

1Documentation Requirements for C645

Ensure all required documentation meets OHIP standards.

  • Keep a copy of the referral request in the medical record.
  • Include the consultant's and referring provider's details on the request.
  • Document the patient's name and health number.
  • Prepare a detailed written report of the consultation with findings and recommendations.

5Weak vs. Strong Note Examples

The strong note provides specific details of the consultation process, including the referring physician's information, a comprehensive description of the assessment and its outcomes, and confirms that a detailed report was sent, meeting OHIP's documentation requirements.

❌ Weak Note

The patient was seen for consultation. Recommendation provided.

✓ Strong Note

Consultation was requested by Dr. Smith (Ref# 12345) for a 70-year-old male diagnosed with lung cancer.

In-depth assessment and discussion of treatment options with patient and family.

Comprehensive report sent to Dr. Smith addressing surgical options and recommendations.

  • Referral details documented
  • Detailed assessment included
  • Written report completed and sent

6Common Reasons This Code Is Missed

1
Lack of Written Referral
Billing C645 without a written request from the appropriate referring provider leads to claim rejection.
2
Inadequate Documentation
Failure to document the consultation thoroughly, including start and end times, can result in billing issues.
3
Exceeding Allowed Frequency
Claiming consultations beyond the specified frequency limits without a valid unrelated diagnosis or correct timing leads to denials.
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8Frequently Asked Questions

What is the fee for billing C645?
The fee for billing the C645 code is CAD 100.15 as a flat fee.
How often can C645 be billed for the same patient and diagnosis?
It can be billed once per two consecutive 12-month periods unless certain conditions allow for a second service.
What conditions qualify for a C645 consultation in thoracic surgery?
Patients with conditions such as empyema, persistent air leaks, or newly diagnosed lung cancer typically qualify.
Is a consultation for a recurrent empyema considered the same diagnosis?
Yes, unless the recurrent condition presents a new clinical complexity distinct from the previous diagnosis.
How should a thoracic surgeon handle multiple in-patient referrals for the same patient?
Ensure each referral meets unique clinical needs and adheres to the 12-month frequency limit rules.
Can C645 be billed for a patient referred from the ER with a collapsed lung?
Yes, if the consultation occurs during an inpatient stay following the emergency department referral.
Does a consultation require a written report when referred from a specialist?
Yes, a detailed written report to the referring provider is always required, regardless of referral source.
In what scenario can C645 be billed virtually?
C645 can be billed for virtual consultations via video call only, not telephone.
Disclaimer: This article is intended as a general educational resource for physicians and billing staff. It does not constitute billing advice or a definitive interpretation of the OHIP Schedule of Benefits. Always verify current billing codes, eligibility criteria, and documentation requirements directly against the official Schedule of Benefits or consult with a qualified medical billing specialist.
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