luckpandaAn invoice is a document a seller sends to a buyer asking to be paid for goods or services that have been supplied, or will be supplied under an agreed arrangement. It records what was sold, when, at what price, how much tax applies, and when and how payment is due.
For the seller, an invoice is the formal start of getting paid and a record of income. For the buyer, it is the evidence behind a purchase, and in many countries the document they need to claim back the tax they paid. For both, it is a business record that tax authorities can ask to see years later.
What an invoice does
An invoice does three jobs at once:
- It asks for payment. It states the amount due, the currency, the due date and how to pay.
- It records a sale. Your books, and your client's books, use it as the source for revenue, expenses and amounts owed.
- It supports tax. Where sales tax, VAT or GST applies, the invoice shows the tax charged. In VAT and GST systems, a valid tax invoice is usually what lets a business buyer reclaim input tax.
An invoice is not the same as a quote, which offers a price before any work is agreed, or a receipt, which confirms money has been received. We compare those in detail in Invoice vs receipt.
What goes on an invoice
The exact list depends on where you are, but almost every tax authority expects the same core details. If your invoice has everything below, it will be acceptable to most clients and most accountants.
| Part | What to write | Why it matters |
|---|---|---|
| Your details | Business name, address, email, tax number if registered | Identifies who is asking to be paid |
| Client details | Client's name and billing address, their tax number for business clients | Identifies who owes the money |
| Invoice number | A unique number, usually sequential, such as INV-2026-0042 | Lets both sides refer to it and keeps your records complete |
| Issue date | The date you issue the invoice, for example 12 Oct 2026 | Starts the payment clock and fixes the tax period |
| Supply date | When the goods were delivered or the work done, if different | Some tax rules use this date, not the issue date |
| Line items | Description, quantity, unit price and tax for each item | Shows exactly what is being charged |
| Totals | Subtotal, tax by rate, and the total due | The amount the client must pay |
| Payment terms | Due date and terms, such as Net 30 | Tells the client when to pay |
| How to pay | Bank details, payment link or other accepted methods | Removes the main excuse for paying late |
A good invoice number system is worth getting right from the start. See our guide to invoice numbers for formats and rules.
A simple invoice example
Here is how the numbers on a small invoice from a US design studio might look. Amounts are written the way the invoice's country writes them.
| Description | Qty | Unit price | Amount |
|---|---|---|---|
| Logo design | 1 | $1,200.00 | $1,200.00 |
| Website page design | 8 | $450.00 | $3,600.00 |
| Revisions (hours) | 12 | $85.00 | $1,020.00 |
| Total due | $5,820.00 |
The same layout works in any country. An Indian invoice would write ₹1,24,500.00 and a German one 12.400,00 €. What changes between countries is mostly tax: which rate applies, how it is shown, and which extra details are compulsory.
Free toolInvoice generatorBill a client in any currency, with tax worked out as you type.Open the invoice generatorTypes of invoice
Most businesses only ever need a handful of invoice types. Each has a specific job.
- Standard invoice. The everyday request for payment after you have supplied something.
- Tax invoice. An invoice that meets the legal requirements of a VAT or GST system, so the buyer can use it to claim input tax. In India this is the GST tax invoice; in the UK it is a VAT invoice.
- Proforma invoice. A preliminary bill sent before supply, often to request an advance or to support an import licence. It is not a tax invoice. Read more in What is a proforma invoice.
- Credit note. Reduces or cancels an invoice you have already issued, for example after a return or a pricing mistake. See What is a credit note.
- Debit note. Increases the amount of an earlier invoice, for example when you undercharged.
- Recurring invoice. The same invoice issued on a schedule, such as a monthly retainer or subscription.
- Commercial or export invoice. Used for goods crossing a border. Customs use it to value the goods and work out duty.
- Interim or progress invoice. Bills part of a larger project as milestones are reached.
How the rules differ by country
There is no single worldwide invoice law. These are the main differences to know. Check the current rules for your situation with an accountant.
United States
There is no federal law that sets out what an invoice must contain. Sales tax is set by states and local areas, and many services are not taxable in many states. In practice, include the core details above and any sales tax charged, and keep records that support your tax return.
United Kingdom
If you are VAT-registered, a full VAT invoice must show, among other things, a unique sequential number, the time of supply (tax point), your VAT registration number, the customer's name and address, a description of what was supplied, the unit price excluding VAT, the VAT rate and the VAT charged. Retailers may issue a simplified VAT invoice for supplies of £250 or less including VAT. If you are not VAT-registered, you must not charge or show VAT.
European Union
The EU VAT Directive (Article 226) lists the details a full VAT invoice needs, including a sequential number, both parties' VAT numbers where relevant, the taxable amount per rate and the VAT due. Member states add their own rules, and several now require electronic invoices in a set format for some transactions.
India
A GST tax invoice must include, under Rule 46 of the CGST Rules, the supplier's GSTIN, a consecutive serial number of up to 16 characters that is unique for the financial year, the recipient's GSTIN if registered, HSN or SAC codes, the taxable value, the rate and amount of CGST, SGST or IGST, and the place of supply for interstate supplies. Larger businesses must also generate e-invoices through the Invoice Registration Portal.
Thresholds, rates and e-invoicing rules change often. Treat this guide as an overview, not tax advice, and confirm the rules that apply to you.
When to send an invoice
Send the invoice as soon as you have earned the right to be paid: on delivery of goods, on completion of the work, or on the date your contract says, such as the first of each month for a retainer. Invoicing late is the most common reason small businesses get paid late. In VAT and GST systems there are also time limits for issuing a tax invoice after the supply, so a delay can create a compliance problem as well as a cash flow one.
Common invoice mistakes
- Reusing or skipping invoice numbers without a record of why.
- Leaving out the due date, so the client decides when to pay.
- Charging tax at the wrong rate, or charging tax when you are not registered.
- Forgetting the client's tax number on a business-to-business invoice.
- Sending an invoice without clear payment details.
- Editing an invoice after it is issued instead of issuing a credit note.
Making your first invoice
You can make an invoice in a word processor or spreadsheet, but you will need to keep the numbering, totals and tax right by hand. An invoicing tool does that for you, formats amounts by the invoice's country and currency, and keeps a record of what you sent. For a step-by-step walkthrough, read How to make an invoice.