how to write an invoice
To write an invoice, give the document a unique invoice number and date, then add your business name and contact details, the client's details, an itemised list of what you supplied with quantities and prices, any tax, and a clear total. Finish with payment terms and how to pay. A professional invoice is a written request for payment, so every line should be unambiguous and easy to act on.
Start with the header and numbering
Every invoice needs the word 'Invoice' clearly at the top so it cannot be mistaken for a quote or a receipt. Add a unique, sequential invoice number (for example INV-001, INV-002) and the date you issued it. Sequential numbering matters because it makes your records auditable and helps both you and your client track what has and hasn't been paid.
If you have agreed a separate due date or reference, include it here too. A purchase-order number, if your client uses them, should sit near the top where their accounts team will look for it.
Add who's billing and who's being billed
List your trading name, address and contact email, plus your company registration or tax number if you have one. Then add the client's name and billing address exactly as they need it for their records. Getting the legal entity name right avoids payment delays when the invoice reaches their finance team.
- Your business name and address
- Your email and phone
- Your VAT or tax number (if registered)
- The client's business name and billing address
- A named contact, if you have one
Itemise the work, then total it
List each product or service on its own line with a short description, quantity, unit price and line total. Add a subtotal, then any tax, then the grand total. Keeping descriptions specific ('Homepage redesign — 12 hours') protects you if a client later queries the bill.
invoiceme builds this layout for you and totals each line automatically, so you can add as many items as you need and export the finished invoice as a PDF, PNG or Word file in one click.
Close with payment terms
State when payment is due (for example 'Net 14' or 'Due on receipt') and exactly how to pay — bank details, a payment link or both. Clear terms set expectations and give you something concrete to refer back to if payment runs late.
make this invoice now
invoiceme builds a clean, properly formatted invoice in your browser and exports it as PDF, PNG, or Word — free, no account, with customisable tax and 20+ currencies.
faq
- Do I need accounting software to write an invoice?
- No. You can write a valid invoice in a document editor or a free browser tool. The legal requirement is the information on it, not the software you used. A dedicated invoice generator just makes it faster and reduces arithmetic mistakes.
- What is the most important thing to include on an invoice?
- A unique invoice number and a clear total with payment instructions. The number makes the invoice traceable, and clear payment details remove any excuse for delay. Missing either is the most common reason invoices stall.
- Should my first invoice be number 001?
- You can start anywhere, but it should be sequential from then on. Some businesses start higher (e.g. 1001) so early clients don't see it's their first invoice. The key rule is no gaps or duplicates.