How to write an invoice

A clear, professional invoice gets you paid faster. Here are the eight things every invoice needs — in the right order — plus a free tool to build one in under a minute.

1. Label it clearly and add an invoice number

Put the word “Invoice” at the top so it can’t be mistaken for a quote or receipt. Give every invoice a unique number (e.g. INV-0001, then INV-0002). Sequential numbers keep your records clean and make it easy to reference a specific invoice when chasing payment.

2. Add your details (the “from”)

Include your business name, your contact email, and — if relevant — your address, phone, and tax/VAT ID. If you’re registered for sales tax or VAT, your tax number usually must appear on the invoice.

3. Add your client’s details (the “bill to”)

Name the person or company you’re billing, plus their email and address. Addressing the invoice to the correct accounts-payable contact is one of the simplest ways to avoid “it got lost” delays.

4. Add the dates

Show the issue date and a clear due date. “Due on receipt,” “Net 14,” or “Net 30” all work — just make the deadline explicit. Vague terms are the number-one cause of late payment.

5. List the line items

For each item or service, show a short description, the quantity (or hours), and the unit price. Let the line total calculate automatically so the math is never wrong. Be specific — “Website design — homepage + 3 inner pages” beats “design work.”

6. Show subtotal, discount, tax, and total

Break the totals down so there are no surprises: subtotal, any discount, tax (with the rate shown), and the final amount due. Make the total the most prominent number on the page.

7. State how to pay

Tell the client exactly how to pay you — bank transfer details, a payment link, or whatever you accept. The easier you make it, the sooner you’re paid. Put this in the notes/terms area.

8. Add a short thank-you or terms note

A one-line “Thank you for your business” plus any late-fee policy keeps things professional and friendly. Done.

Common mistakes to avoid

• No due date — “whenever” means “never.” Always set one.
• Reusing invoice numbers — breaks your bookkeeping and looks careless.
• Vague line items — invites questions and delays approval.
• Forgetting tax details — if you’re tax-registered, this can make the invoice invalid.
• No payment instructions — don’t make the client hunt for how to pay you.

Frequently asked questions

Do I need accounting software to send an invoice? No. A clean PDF with the eight elements above is perfectly valid. You can make one free with Plainvo in under a minute.

What’s the difference between an invoice and a receipt? An invoice requests payment; a receipt confirms payment was made. See what to include on an invoice for the full checklist.