An invoice is simply a document that tells a client what they owe you, for what, and how to pay it. You don't need accounting software or a design background to write one — you need eight pieces of information laid out clearly. This guide walks through each one, then shows you the fastest way to produce a professional invoice you can send today.
In a hurry? Open the free invoice generator, fill in the fields below as you read, and download your finished PDF. Nothing to install, no signup.
What every invoice must include
Whether you're a freelancer sending your first invoice or a small business billing a regular client, these eight elements are the backbone of every professional invoice:
- The word "Invoice". State plainly at the top that the document is an invoice, so there's no confusion with a quote or a receipt. (In Australia, if you're registered for GST, this becomes "Tax Invoice" — more on that below.)
- A unique invoice number. A sequential reference like INV-0001 that you never reuse. It lets both you and your client refer to a specific bill.
- Your details. Your business or trading name, address, email and phone — and your business number (an ABN in Australia).
- Your client's details. Who you're billing: their name or business name and contact details.
- Issue date and due date. When you raised the invoice and when you expect to be paid.
- An itemised list. A line for each product or service with a description, quantity and unit price. Specific descriptions get approved faster than vague ones.
- Tax and totals. Any tax (such as 10% GST), the subtotal, and the final total the client needs to pay.
- Payment instructions. How to pay you — bank transfer details, PayID, a payment link — plus your terms.
Step by step: filling in each section
1. Add your business identity
Start with who you are. Put your business name (or your own name if you're a sole trader) at the top, along with your address, email and phone number. If you have a logo, add it — it takes seconds and makes the invoice look established. This information rarely changes, so a good invoice tool saves it for next time.
2. Add the invoice number and dates
Give the invoice a number and set the issue date to today. Then set a due date based on your payment terms. Being explicit — "Due 24 July 2026" rather than just "Net 14" — removes any ambiguity and gives late payers one less excuse.
3. List what you're charging for
Add one line per item. For a service, that might be "Website design — 10 hours @ $150". For products, list quantity and unit price. The line total (quantity × rate) should calculate automatically so you never make an arithmetic error in front of a client.
4. Apply tax and show the total
If you charge tax, add it as a clear line. Australian businesses registered for GST add 10%. Your invoice should then show a subtotal, the tax amount, and a bold final total. If your client has already paid a deposit, subtract it and show the remaining balance due.
5. Tell them how to pay
This is the step people forget, and it directly delays payment. Include your bank name, BSB and account number (and PayID, if you're in Australia), or a payment link. The easier you make paying, the sooner it happens.
Choosing your payment terms
Payment terms set the clock on when you get paid:
- Due on receipt — payment expected immediately.
- Net 7 / Net 14 — due in 7 or 14 days; common for freelancers and small jobs.
- Net 30 — due in 30 days; standard for larger businesses, but slower for your cash flow.
Shorter terms tend to get paid sooner. If cash flow matters — and for most small businesses it does — lean toward Net 7 or Net 14 and state the due date clearly.
Small details that get you paid faster
- Send it immediately. The payment clock only starts once the invoice lands. Send it the day the work is done.
- Be specific in descriptions. "Bathroom tiling — labour, 16 hrs" beats "work done" and prevents back-and-forth.
- Quote their reference. If your client gave you a purchase order number, put it on the invoice so their accounts team can approve it without asking.
- Follow up promptly. A polite reminder the day after the due date resolves most late payments.
The fastest way to write an invoice
You can build an invoice in a word processor or spreadsheet, but you'll spend time on formatting and risk maths errors. A dedicated tool handles the layout and calculations for you. Our free invoice generator lays out all eight elements above, calculates your totals as you type, lets you add a logo, and downloads a clean PDF — with no signup and nothing stored on our servers. If you're in Australia and need a GST tax invoice, use the Australian tax invoice generator, which adds an ABN field, 10% GST and a live ATO-compliance checklist.
Once you're invoicing the same clients every month, a full invoicing app saves even more time. InvoiceSonic sends invoices, tracks who has paid, and chases late payers automatically — and it's free too.
Frequently asked questions
What should an invoice include?
The word "Invoice", a unique invoice number, your business name and contact details, your client's details, the issue and due dates, an itemised list of goods or services with quantities and prices, any tax, the total due, and how to pay.
How do I number invoices?
Use a simple sequential series such as INV-0001, INV-0002, and never reuse a number. Sequential numbering keeps your records auditable and lets you reference a specific invoice easily.
What are standard invoice payment terms?
Common terms are Net 7, Net 14 and Net 30 — payment due 7, 14 or 30 days after the invoice date. "Due on receipt" means immediately. Shorter terms generally get you paid faster.
Do I need software to write an invoice?
No. You can write an invoice in a free online generator, download it as a PDF, and email it to your client — no account or software required.