Write-off adjustments can be the total amount due on an account, the amount of an invoice, or partial amounts. Write-off adjustments are applied to debt (see the Adjustment Types topic in Admin Console Data management help).
Click the Balances tab on the Customer window.
Right-click and select New > Adjustment. This displays the Add Adjustment window.

Enter the amount of the write-off in the Amount field.
Select a write-off Adjustment Type.
Note
For this adjustment to be included in the Write-Off report, the Adjustment Type must have been set up with "Is Write Off" selected.
To allocate the adjustment, under Adjustment Allocation:
Select the invoice number in the Apply to Invoice Number field to write off the complete invoice or to apply a partial write-off to a specific invoice.
Select the appropriate invoice category in the Apply to Invoice Category field for a partial write-off. This field is required for a partial write-off.
Click Save.