Time & Materials and Fixed Bid are billing types associated with projects.
A Time & Materials project is billed based on the number of hours worked, at the hourly, daily, or monthly fixed billing rates assigned for that project.
A Fixed Bid project is billed using a flat amount, regardless of the number of hours worked. This flat amount can be applied to the project as a whole, or to each week or month of the project. Since Fixed Bid projects are duration-based, they require a start and end date.
You must choose the type of billing you want to use when you create a new project – you cannot change the billing type later. When you add a project, select the applicable Billing Type option from the Add New Project dialog.
Refer to Setting up your project for billing for information on that topic.
‘Materials’ means you can bill the client for expenses incurred, if applicable.