Billing less than the billable amount
If you bill for less than the full billable amount, the remaining amount will continue to appear in the Prepare Time Billing Invoice window as work in progress, and you'll be able to bill for it at a later date. The remaining amount also will be reflected in the Single Slip Entry view of the Enter Activity Slip window when you view the activity slip's details.
If you're giving the customer a discount or writing off part of the billable amount, you may not want the remaining amount to appear as still payable. In that case, also enter a negative amount in the Adjustment field equal to the remaining billable amount. The Left to Bill amount will be zero and the activity slip will be removed from the Prepare Time Billing Invoice window.