You use Billing groups to combine projects together for the purpose of billing a client.
You create billing groups so that you can bill several projects together on one invoice. This feature is useful if you have multiple projects for the same client and the client wants to receive one invoice for all projects.
If you use the Multicompany feature, the company that "owns" the main project in the billing group (via the organization structure) is the company that generates the invoice for the entire billing group.
Phases and Tasks
You can specify phases or tasks for any of the projects in a billing group. However, an invoice can be complicated if it includes several projects with phases (or phases and tasks). To reduce this confusion, Deltek recommends that the projects in your billing groups not contain phases or tasks.
If you do specify phases or phases and tasks for your subprojects, you can enter separate billing terms by phase or by task. Again, this causes the invoice to be lengthy and complicated and is not recommended.
Charge Types
To add a subproject to a billing group, the project must have the same charge type (regular, overhead, promotional) as the main project. If the project types don't match, you need to create a new project with the correct charge type and transfer data into it, before you can add the project to the billing group.
If you attempt to add a subproject and Vision displays the message "Subproject must be the same charge type as the Main project," ensure that you have selected the correct project to add as a subproject. If you are sure that you've selected the correct project, you can key convert the project with the wrong charge type into a new project with the correct charge type.
Multicurrency
If you use the Multicurrency feature, each sub-project must have the same billing currency as the main project.