To write an invoice, create a clearly labelled document that states who you are, who you are billing, what you sold, how much is owed, when payment is due, and how to pay you. The fastest way is to fill in each field once and let a generator format and total it for you, but here is exactly what a complete, professional invoice needs.
What to put on an invoice:
- The word "Invoice" at the top so it is unmistakable. In Australia, if you are registered for GST you must title it "Tax Invoice".
- Your business details: your business or trading name, address, phone and email. In Australia, include your ABN (the ATO requires it on a tax invoice). In the US, include your business name and, where relevant, your tax ID (EIN or TIN).
- A unique invoice number. Number invoices sequentially (for example INV-0001, INV-0002) so each one is easy to track, reference and reconcile.
- The invoice date (when you issued it) and the due date (when payment is expected). A clear due date is what makes your payment terms enforceable.
- Your client's details: their name or business name and their billing address. In Australia, for tax invoices of 1,000 dollars or more, you must also show the buyer's identity or ABN.
- An itemised list of goods or services. For each line, show a brief description, the quantity, the unit rate, and the line amount. This is the heart of the invoice and prevents disputes.
- A subtotal of all line items before tax.
- A tax line if applicable. In Australia, GST is 10 percent and the GST amount must be shown separately, or you can state "Total price includes GST" when GST is exactly one-eleventh of the total. In the US, add the applicable sales tax for your state.
- The total amount due, in your currency, shown prominently.
- Payment terms, such as Net 7, Net 14 or Net 30, stating how many days the client has to pay.
- Payment details so the client can actually pay: bank account name, BSB and account number, or PayID for Australian bank transfers, plus any other method you accept.
A few practical tips. Invoice promptly, ideally the day you finish the work, because the clock on getting paid only starts once the invoice is sent. Always number invoices sequentially with no gaps. And keep a copy of every invoice for your records; the ATO requires Australian businesses to retain records for 5 years, and the IRS recommends US businesses keep them for around 7 years.
InvoiceSonic builds all of this for you automatically. You enter your details, add line items, and it calculates the subtotal, tax or GST, and total, then outputs a clean, professional PDF in about 60 seconds, with no signup required. This is general information, not tax or legal advice, so check the current rules for your situation or ask a registered tax professional.