How to write an invoice: a simple step-by-step guide

What an invoice is for

An invoice is a request for payment. It tells your customer what they bought, how much they owe, by when, and how to pay. It is also a record for you, your customer and the tax office, so it needs to be clear and complete.

The details every invoice should have

• The word "Invoice" (or "Tax invoice" if you are registered for VAT or GST and your country requires it).
• A unique invoice number. Number invoices in sequence (INV-0001, INV-0002) and never reuse a number.
• The invoice date, and the date you delivered the goods or service if it is different.
• Your business name, address and contact details, plus your logo if you have one.
• Your customer's name (or company) and address.
• A line for each item: description, quantity, unit price and line total.
• Subtotal, any discount, shipping, tax, and the total due.
• Payment terms (for example "Due on receipt" or "Net 30") and the due date.
• How to pay: bank details, a payment link, or a UPI QR in India.

Extra details if you charge VAT, GST or sales tax

Once you are registered for tax, most countries also ask for:

• Your tax registration number (VAT number, GSTIN, ABN, TRN and so on).
• The tax rate and tax amount, often for each line or each rate.
• Your customer's tax number for business-to-business sales in some countries.
• Totals before and after tax.

Step by step

• Open a template or an invoice generator and pick your country, so the currency and tax match.
• Add your business details once; good tools remember them.
• Add the customer, the invoice number and the dates.
• List the items with quantities and prices, and choose the tax rate.
• Check the totals, add your payment details and a short thank-you note.
• Download the PDF or send it by email or WhatsApp, and keep a copy.

Common mistakes that delay payment

• No due date, or vague terms like "pay soon".
• Missing purchase order (PO) number when the customer gave one.
• Charging tax when you are not registered, or forgetting it when you are.
• Duplicate or out-of-order invoice numbers.
• Bank details with a typo. A payment link or QR code avoids this.

Check your country's rules

Each country adds its own requirements. See the invoice rules for the UK, USA, Canada, Australia, UAE, Singapore, New Zealand, Ireland and South Africa on the country pages, or the GST invoice guide for India.