A Statement of Work (SOW) is a project-specific document issued under a Master Services Agreement that defines deliverables, timelines, pricing, and acceptance criteria for a discrete engagement. The Federal Acquisition Regulation requires statements of work in most federal procurement contracts (FAR 48 C.F.R. § 37.602, https://www.acquisition.gov/far/37.602).
The SOW is the operational document that activates work under an MSA framework. While the MSA handles legal boilerplate once, each SOW specifies: (1) scope — exactly what will be delivered; (2) schedule — milestones and final delivery date; (3) fees — fixed price, time-and-materials rates, or retainer; (4) acceptance criteria — how the buyer confirms satisfactory completion; (5) change order triggers — what events require a new SOW or SOW amendment. SOWs are legally binding once executed by both parties and automatically incorporate the MSA terms by reference. They should not contradict the MSA; where conflicts exist, MSA terms typically control unless the SOW explicitly overrides a specific provision. Financing implications: SOWs represent earned (or earnable) revenue. For accounts receivable financing and invoice factoring, lenders may advance against invoices issued under a SOW — provided the SOW is signed, deliverables are accepted, and no unresolved disputes exist. Factoring advances are typically 70-90% of face value for commercial SOW-based invoices, per lender underwriting guidelines. Unapproved SOW scope changes ('scope creep') that lead to disputed invoices are a top cause of factoring facility friction. For SBA-backed working capital lines, the SBA's SOP 50 10 acknowledges project-based revenue businesses but requires lenders to assess revenue concentration risk — a single SOW client representing >50% of revenue may require additional collateral or concentration reserves (https://www.sba.gov/document/support-sba-standard-operating-procedures-sop-50-10).
Most invoice factoring facilities require the invoice to represent fully completed, delivered, and accepted work. An invoice billed against an incomplete SOW milestone may not qualify. Some factoring products allow progress billing under an approved SOW — but only for accepted milestone completions, not anticipated future work. Confirm with your factor before billing ahead of acceptance.
A disputed SOW invoice becomes a 'dilution' event in a factoring or ABL facility. The lender will typically freeze availability against that invoice until the dispute resolves, and chronic disputes above a dilution threshold (often 2-5% of total factored receivables) may trigger a facility review. Clear SOW acceptance criteria — written, measurable, and pre-agreed — are the best protection against factoring dilution.
Related but distinct. A purchase order (PO) is typically used for goods or standardized services at a fixed unit price; it is buyer-issued and less negotiated. An SOW is typically used for custom services, is jointly negotiated, and includes detailed scope and acceptance criteria. Both can serve as the basis for financing receivables, but lenders generally prefer SOW-backed receivables for professional services because the scope and acceptance obligations are more explicitly documented.