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.
A104-2017 is better suited for projects with slightly more complexity, including detailed designs, use of subcontractors, and the potential for hazardous materials. A105-2017 is ideal for simpler projects that involve a clear scope, defined costs, and minimal risk.