The total write-off amount can be calculated as the the difference between the total charge for the visit and the sum of what the patient pays and what the insurance reimburses:
Total Write-Off = Total Charge - (Patient Copay + Insurance Reimbursement)
Total Write-Off = $630.00 - ($20.00 + $450.00)
Total Write-Off = $630.00 - $470.00
Total Write-Off = $160.00
So, the total write-off amount in this scenario is $160.00.