How to Invoice a Client: A Step-by-Step Guide

Invoicing a client well is half presentation, half process. A clear, professional invoice gets processed faster by the client’s finance team, signals that you run a serious business, and gives you a paper trail if a payment dispute ever arises. This guide covers exactly what to include and how to send it.

What every invoice must include

• A unique invoice number (sequential numbers like INV-0042 keep your records clean)
• Your business name, address, email and phone number
• The client’s name and billing address — exactly as their accounts team expects it
• An issue date and an explicit due date
• Line items: a description, quantity and unit price for each piece of work
• Subtotal, tax, any discount or shipping, and the total due
• Payment instructions and terms (e.g. "Payment due within 14 days by bank transfer")

Choosing payment terms

Net 30 — payment due 30 days from the invoice date — is the corporate default, but freelancers and small businesses can and should use shorter terms. Net 14 is widely accepted, and "due on receipt" is reasonable for small projects. Whatever you choose, write the actual due date on the invoice rather than relying on the client to calculate it.

For larger projects, invoice in stages: a deposit before work begins, then milestone or completion payments. A 30–50% deposit dramatically reduces your risk on new clients.

Sending the invoice

Always send a PDF, not an editable document or a screenshot. Attach it to a short email that names the invoice number, the amount and the due date in the body — finance teams often skim the email rather than open the attachment immediately. Ask whether the client needs a PO number on the invoice; many medium and large companies won’t process an invoice without one.

Following up on late payment

Send a polite reminder the day after the due date — most late payments are administrative oversights, not refusals. If a second reminder a week later goes unanswered, call. For persistent late payers, shorten terms, require deposits, or add a late-payment fee to your terms (where local law permits, 1–1.5% per month is typical).