A statement of work (SOW) is an important document that outlines a project's scope, timeline, and cost between two parties usually a customer and a supplier. An MSA is an overarching contract that lays out the general terms and conditions governing the business relationship between a service provider and customer.A master service agreement (MSA) is a fundamental contract outlining the scope of the relationship between two parties. An SOW should always state what the Services Agreement says it states, such as the Services, the Timeline, and the Fees.