The short answer
An invoice needs your business name and contact details, the customer's name, a unique invoice number, the issue date, a line for each item with quantity and price, any tax, the total, and how and when to pay. If you're registered for sales tax, VAT or GST, add your registration number.
On this page
What is an invoice?
An invoice is a request for payment. It lists what you sold, what it costs and how to pay. It is different from:
- A quote or estimate, which says what something will cost before the customer agrees.
- A receipt, which confirms that payment has been made.
What should an invoice include?
- The word “Invoice” at the top (or “Tax Invoice” for GST in India).
- Your business name, address and contact details. Add your logo if you have one.
- The customer's name and address, and their email if you send it by email.
- A unique invoice number.
- The issue date, and a due date if they pay later.
- A line for each item or service: a clear description, quantity, unit price and line total.
- Subtotal, discount, tax and shipping, each on its own line.
- The total due, in bold, with the currency.
- How to pay: bank details, a payment link, or the methods you accept.
- Your tax registration number, if you are registered for sales tax, VAT or GST.
How should you number invoices?
Use one running sequence and never reuse or skip a number. Simple patterns work best:
INV-0001,INV-0002,INV-00032026-001,2026-002if you prefer to restart each year
Tax offices look for gaps and duplicates, and a clean sequence makes your own bookkeeping easier. In India, GST invoice numbers can be at most 16 characters and must be unique for the financial year.
What payment terms should you use?
- Due on receipt: the customer pays straight away. Common for one-off sales to individuals.
- Net 7, Net 14 or Net 30: payment is due that many days after the invoice date. Common for business customers.
- Deposit: part up front, the rest on delivery. Useful for custom work.
Write the due date on the invoice as a date, not only as “Net 14”, so there is no argument about when it was due.
What tax details do you need?
It depends on where you are, and if your business is registered for tax. This is a general overview, not tax advice, so check with your tax office or an accountant.
- United States: there is no federal invoice format. If you collect sales tax, show it as its own line at your state and local rate.
- Canada: if you are registered for GST/HST, show your registration number and the tax charged. The CRA asks for more details as the sale gets larger.
- United Kingdom: if you are VAT-registered, your invoices need your VAT number, the VAT rate and the VAT amount for each item. If you are not registered, don't charge VAT.
- India: a GST tax invoice shows your GSTIN, the customer's GSTIN if they are registered, HSN or SAC codes, the place of supply, and the tax split as CGST and SGST within your state or IGST between states. Composition scheme sellers issue a bill of supply instead, and larger businesses must also generate e-invoices on the government portal.
Common invoice mistakes
- Vague descriptions such as “Services” or “Items”. Say what it was.
- No due date, so the customer doesn't know when to pay.
- Editing an invoice after sending it. Issue a credit note and a new invoice instead.
- Forgetting how to pay. Every invoice should say exactly how.
Do you need invoices for online orders?
If customers pay at checkout, the order confirmation email usually does the job of a receipt, and you only need to send an invoice when a business customer asks for one. Where invoices really eat time is when orders come in through DMs and you write each one up by hand.
With a free E2C store, customers check out on their own, pay by card or PayPal, and get an order email straight away. Every order has its own page in your dashboard that you can print for your records. See how it works.