You can adjust account or bill unit charges on the item level. You can adjust service charges on the item level or on the event level.
To adjust an item:
On the account page, click the Bills tab.
In the Bills section, select the bill you want to work with.
To locate a bill, see "Finding a Bill".
Select the charge.
The Charges dialog box appears.
Click a charge description.
A dialog box opens.
Click New Adjustment.
The Item Adjustment dialog box opens.
For Adjustment, enter the amount or percent to adjust.
For Effective, enter a start date.
(Optional) Select Exclude taxes from the adjustment.
Select a reason.
(Optional) Enter notes.
Click OK.