Guide
How to Write an Invoice
An invoice is a request for payment that identifies both parties, describes what was supplied, states the amount owed and sets a deadline. Everything else on the document exists to remove an excuse for not paying it.
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How do you write an invoice?
Write the word Invoice at the top, add your details and the client's, give it a unique number and an issue date, list what you supplied with quantities and rates, show the subtotal, tax and total, state the due date, and add payment instructions.
That order is not arbitrary. A person approving an invoice reads top-down looking for three things: is this for us, what is it for, and how much. Put those where they expect them and approval takes seconds.
What should an invoice contain?
At minimum: the word "invoice", a unique invoice number, the issue date, your business name and address, the client's name and address, a description of goods or services, the amount due, any tax, the total, and the payment due date.
Additional requirements depend on where you trade and whether you are registered for a sales tax or VAT. Registered businesses usually have to show their registration number, the tax rate and the tax amount separately. Check the specific requirements for your jurisdiction.
The nine parts of an invoice, in order
- 1
1. Label and number
The word Invoice, plus a unique sequential number. Without a number, neither side can reference the document.
- 2
2. Your details
Trading name, address, email, phone and tax registration number if you have one. A logo helps recognition but is optional.
- 3
3. Client details
The legal entity being billed and its billing address. Add the contact name below the company, not instead of it.
- 4
4. Dates
Issue date and payment due date. Add the service period if the work spanned weeks.
- 5
5. Reference
Their purchase order, project name or job number. This is what lets a finance team match the invoice.
- 6
6. Line items
One row per deliverable: description, quantity, rate, line total. Describe outcomes, not internal tasks.
- 7
7. Totals
Subtotal, any discount, tax rate and amount, shipping if applicable, then the grand total clearly emphasised.
- 8
8. Payment instructions
How to pay: bank account details, accepted methods, or a payment link. Make it impossible to have to ask.
- 9
9. Terms and notes
Payment terms in words, late-fee policy if you have one, and a short thank-you. Keep it factual.
A worked example
A freelance designer completes a brand refresh for a client in October. She issues invoice INV-2026-0042 on 1 October with Net 14 terms, so the due date is 15 October. The reference field carries the client's PO number, PO-8871.
| Description | Qty | Rate | Amount |
|---|---|---|---|
| Brand discovery workshop (half day) | 1 | 450.00 | 450.00 |
| Logo design, three concepts and two revision rounds | 1 | 1,800.00 | 1,800.00 |
| Brand guideline document | 1 | 600.00 | 600.00 |
| Additional artwork, hourly | 6 | 85.00 | 510.00 |
| Subtotal | 3,360.00 | ||
| Discount (5% agreed retainer rate) | -168.00 | ||
| Tax (20% on 3,192.00) | 638.40 | ||
| Total due 15 October 2026 | 3,830.40 |
Wording that shortens the payment cycle
- Write the due date as a date, not only as a term. "Net 30" is not a deadline to a busy approver.
- Describe deliverables the client recognises. "Homepage and three landing pages, final files delivered" is approvable; "design work" invites a question.
- Put the payment method above the notes, not in the footer.
- Reference the approval that authorised anything outside the original scope.
- State a late fee only if your contract supports it, and state the rate and start date.
Common mistakes
The four that cause most delays are: a missing or duplicated invoice number, billing a contact instead of the company, omitting the purchase order reference, and arithmetic that does not survive a check. The first three are habits; the fourth is what a generator removes, because totals, discount ordering and tax are calculated rather than typed.
Frequently asked questions
Published 18 September 2026. Last updated 18 September 2026. Written by the Free Invoice Generator team. General invoicing information, not tax or legal advice.
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