Estimates and invoices look similar — both have line items, totals, and a customer attached — but they sit at opposite ends of a deal.
- An estimate is a promise to charge if the customer accepts. The customer's decision (approve, reject, ignore) is the lifecycle.
- An invoice is a demand for payment once the work is done. Payment is the lifecycle.
When to use which
Send an estimate when:
- The customer hasn't agreed yet.
- You need a written quote with a valid until date so price isn't open-ended.
- The work is scoped but not delivered.
Send an invoice when:
- The customer agreed (verbally or via an approved estimate).
- The work is delivered, in progress, or under a milestone schedule.
- You're collecting payment.
The bridge
When an estimate is approved and the work is delivered, convert it to an invoice. Vertiqa carries line items over and links the records, so reporting can see the full chain: opportunity → estimate → invoice → payment.
What if the scope changes?
Don't edit a sent estimate. Send a revision; the original stays on the record. Same for invoices: void and re-issue rather than editing in place. The audit trail is what makes disputes resolvable.