How Subcontractors Invoice Prime Contractors
A step-by-step guide for 1099 independent contractors, tradespeople, and freelancers billing general contractors and prime agencies.
Invoice-Gen Editorial Team provides practical business guidance, compliance advice, and invoicing tools for 1099 contractors, trade specialists, and freelancers.
Key Article Takeaways
- Include your Tax Identification Number (TIN) or SSN matching your W-9 form.
- Reference the prime contractor's Master Services Agreement (MSA) or PO number.
- Itemize completed milestone deliverables or approved timesheets.
- Comply with 'Pay-When-Paid' or 'Pay-If-Paid' contractual billing clauses.
- Submit non-editable PDF invoices directly to Accounts Payable.
Navigating Subcontractor Billing Workflows
Subcontractors play a vital role in construction, IT consulting, creative agencies, and specialized trade projects. Unlike billing direct end-clients, invoicing a general contractor or prime agency involves strict corporate approvals, purchase order matching, and tax compliance rules (such as Form W-9 in the US). Following proper subcontractor invoicing standards ensures your bill passes accounting review without delay.
Step-by-Step Execution Guide
1. Verify Prime Contractor PO & Project Numbers
Obtain the official Purchase Order (PO) or Project Code from the general contractor before drafting your invoice.
2. Match Invoiced Names with W-9 Tax Records
Ensure your business name, DBA, and Tax ID on the invoice exactly match the Form W-9 submitted to the prime contractor.
3. Itemize Tasks by Contract Line Items
Break down labor hours or milestone deliverables according to the original subcontract agreement scope.
4. Attach Supporting Documentation
Include signed daily work logs, supervisor sign-offs, or material expense receipts alongside your invoice.
5. Route Invoices to the Designated Accounts Payable Email
Send your PDF invoice directly to the prime contractor's AP department (e.g. ap@primecompany.com) rather than just a field manager.