An Ad-Hoc Invoice would be useful if you want to create an invoice for charges that weren't incurred during or outside the normal billing cycle.
Step 1. Select the Account
Under the Account tab, select the account you would like to create an Ad-Hoc invoice for, this will display the account details.
Step 2. Create the Ad-Hoc Invoice
Near the top right under the "Select an Action" dropdown menu, one of the options will be "Create Ad-Hoc Invoice". This is shown below.
Click the Create Ad-Hoc Invoice to begin the process.
The next step will involve adding charges manually to your new invoice. This step is detailed in Manually Adding Charges to an Invoice section.