glossary

Invoice

operations & toolsreviewed by the Forge team · 8 June 2026

The document an agency issues to request payment for work done - listing the services, amounts, terms and due date.

For example, on hitting a milestone the agency issues an invoice for that stage, referencing the SOW and due net 15. Prompt, clear invoicing tied to deliverables is what keeps cash arriving on schedule.

Why it matters to agencies: invoicing is the unglamorous step that actually turns delivered work into cash - and slow or sloppy invoicing is a common, self-inflicted cash-flow problem. Tying invoices to milestones and chasing them promptly keeps accounts receivable low and the business liquid.

What an invoice includes

  • What is being billed, with the SOW reference
  • Amounts and any tax
  • Payment terms and due date
  • How to pay
  • A unique invoice number
common mistakes
  • Invoicing late, which delays getting paid.
  • Vague line items that prompt queries.
  • No clear due date or payment method.
common questions
What is an invoice?

The document an agency issues to request payment for work done - listing the services, amounts, terms and due date.

What should an agency invoice include?

The services or milestone billed, amounts, any tax, the payment terms and due date, and a reference to the SOW or project.

When should agencies invoice?

Promptly - on deposit, at milestones, or on a regular retainer date - rather than batching it up, so cash arrives sooner.

How do invoices affect cash flow?

Delivered work only becomes cash once invoiced and paid, so prompt invoicing and short terms keep cash flowing and accounts receivable low.

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