As long as you have connected the MSC to the IC Pro platform (you have to go there), then invoices are submitted automatically. this of course is only for Sassie MSCs. When you submit a report, you will see a message that says an invoice has been submitted on your behalf.
The only companies (Sassie or not) which quickly come to mind that require a separate invoicing step are Maritz (done on their website) and Cirrus, which is done on paper which is scanned and emailed to them. There might be some others.
Shopping Southeast Pennsylvania, Delaware above the canal, and South Jersey since 2008