How to write an invoice

Updated 2026-07-05 · Billotter

An invoice is a request for payment that also doubles as your record of the sale. Get its eight parts right and you get paid faster with fewer questions. Here is exactly what goes on one, in order, with an example you can copy.

Whether you write it in a word processor, a spreadsheet or a dedicated generator, a professional invoice is the same document: a clear, itemized request for payment addressed to a specific client, carrying a unique number and a due date. Nail those and the rest is formatting.

The 8 things every invoice needs

• The word "Invoice" — plus your logo or business name at the top. It tells the recipient's accounts payable team what this is at a glance, so it lands in the right pile.
• Your details — business name, address, email, and any tax or registration number you are required to show. This is who the money goes to.
• The client's details — the billing name and address of the person or company that owes you, not just the person you email with. Large clients pay the "Bill to" name on the invoice.
• A unique invoice number — sequential and never reused. It is how both of you refer to this specific bill later. More on numbering.
• Issue date and due date — when you sent it and when payment is expected. A due date is not optional; "whenever" is why invoices sit.
• Itemized lines — a row per thing you are charging for, each with a description, quantity, unit rate, and line total. Detail here prevents disputes later.
• Subtotal, tax and total — the math, shown. If you charge sales tax or VAT, it gets its own line so the total is defensible.
• Payment terms and how to pay — the terms (e.g. "Net 14"), the methods you accept, and the details needed to pay you. Make paying the easy part.

How to write an invoice, step by step

1. Start with a header the client trusts

Your business name or logo, the word "Invoice", and your contact details. It does not need to be fancy — it needs to look like it came from a real business, because that is the first thing that gets an invoice paid instead of queried.

2. Give it a unique number

Assign a sequential number like INV-0001 and never repeat one. Numbers are how you and your client's bookkeeper both find this exact invoice in six months. A tip most people miss: start your very first number at something like INV-1001 rather than 0001, so a new client cannot tell they are your first.

3. Address it to the right entity

Put your client's legal billing name and address under "Bill to". If they gave you a purchase-order (PO) number, add it — for many companies, an invoice without the PO number is an invoice that does not get paid.

4. List what you did, line by line

One row per deliverable or unit of work: a plain-English description, the quantity (hours, items, words), your rate, and the line total. "Website homepage — design and build (12 hrs)" survives a finance review; "web work" invites an email.

5. Add up the totals, tax included

Show the subtotal, then any tax or discount on its own line, then the grand total in bold. If you are registered for sales tax or VAT, the tax line and your registration number are usually legally required — check the rules where you operate.

6. State the terms and the due date

Spell out when payment is due ("Payment due within 14 days" or a specific date) and any late-payment policy. Vague terms are the single biggest cause of slow payment. See payment terms explained.

7. Tell them exactly how to pay

Bank transfer details, a payment link, or a "pay by QR" code — whatever you accept, put the actual details on the invoice. Every extra step between the invoice and the payment is a day added to how long it takes.

8. Send it, and keep a copy

Email the PDF (PDFs cannot be accidentally edited and look the same on every device) and save a copy for your own records and taxes. Then log the invoice number so the next one continues the sequence.

A worked example

Here is what the itemized middle of a simple invoice looks like in practice:

Terms: Payment due within 14 days of the invoice date. Bank transfer or card via the link below.

Common mistakes that delay payment

• No due date. "Payable upon receipt" with no date is an invitation to pay later. Give a specific day.
• Missing PO or reference number. Business clients route payment by these; leaving them off sends your invoice into a holding pattern.
• Vague line items. "Consulting — $2,000" gets questioned; "Strategy consulting: discovery phase (10 hrs @ $200)" gets paid.
• Reused or missing invoice numbers. They break your records and look unprofessional. One sequence, no gaps, no repeats.
• Burying how to pay. If the client has to email you to ask how to send money, you have added a week. Put the details right there.

Once you have the parts down, an invoice takes about two minutes. A pre-filled template for your line of work makes it faster still.

Frequently asked

Keep reading

• What to include on an invoiceThe complete checklist of required fields
• Invoice payment terms explainedNet 30, Net 15, Due on Receipt & how to choose
• Invoice vs estimate vs quote vs receiptFour documents people mix up, sorted out

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