An invoice is a commercial document a seller issues to a buyer that lists the goods or services supplied, along with quantities, unit prices, and the total amount due. It functions as a formal request for payment and as a record both sides can reference for accounting, tax, and dispute purposes. In B2B sales, an invoice usually comes after a quote has been negotiated and accepted, once the order is confirmed.
What an invoice includes
A standard B2B invoice carries an invoice number, issue date, and payment due date, plus the seller and buyer details (often including tax registration numbers). It itemizes each line with description, quantity, unit price, and line total, then shows subtotals, any discounts, tax or VAT, shipping, and the final balance due. Payment terms such as Net 30 and accepted payment methods usually appear near the total.
Invoice vs. quote
A quote is an offer: it proposes prices and terms before the buyer commits. An invoice is a demand for payment issued after the buyer agrees and the order is placed. The two often share the same line items, which is why an accepted quote is commonly converted straight into an invoice rather than re-keyed.
How it works on Shopify
Shopify does not have a separate “invoice” object in the way accounting software does. In practice, a confirmed B2B order becomes a draft order, and Shopify can send the buyer an invoice link that routes them to checkout to pay. Tools that manage the earlier quoting stage can turn an accepted quote into a real Shopify draft order, so the itemized figures the buyer already approved carry through to payment without manual retyping.
Example
A distributor requests 500 units. The seller sends a quote at a negotiated per-unit price. The buyer accepts, so the seller issues an invoice for 500 units at that price, plus tax and freight, with Net 30 terms and a due date 30 days out.