A complete invoice gets paid; an incomplete one gets a reply asking questions. Use this checklist before you send anything: the essential fields no invoice should ship without, the optional ones that earn their place in specific situations, and a filled example showing everything in position.
The essentials: never send without these
| # | Field | Why it matters |
|---|---|---|
| 1 | The word "Invoice" | Instantly identifies the document for the client and their bookkeeping software. |
| 2 | Unique invoice number | The reference both sides use in emails, payment records, and disputes. See Invoice Numbering: Schemes That Scale. |
| 3 | Issue date | Anchors the payment terms — "Net 30" counts from here. |
| 4 | Your business name and contact details | Who is owed the money, and where to send questions. Include your address; many companies require it to process payment. |
| 5 | Client's business name and address | Who owes the money. Use their full legal/registered name — a mismatch can bounce your invoice back from accounts payable. |
| 6 | Itemized line items | What you're charging for: description, quantity, rate, line total. Vague single lines ("Services — $3,000") invite scrutiny; itemized lines get approved. |
| 7 | Subtotal, tax (if any), and total due | Show the math. The total should be visually unmissable. |
| 8 | Due date or payment terms | "Due October 15" or "Net 14." Without it, "whenever" becomes the default. |
| 9 | How to pay | Bank details, or whatever method you accept. Every step the client has to ask about adds days. |
Conditionally required: depends on your situation
- Tax ID / registration number. If you're registered for GST, VAT, or sales tax, your registration number generally must appear, and tax should be shown as its own line with the rate. If you're not registered, leave it off rather than inventing one.
- Client's tax ID. Common on business-to-business invoices in GST/VAT systems.
- Purchase order (PO) number. If the client issued one, it's effectively mandatory — invoices without the PO number often can't be processed at all. Ask before your first invoice.
- Currency. Essential the moment you and your client are in different countries. State it explicitly (USD vs CAD vs AUD is real money).
Optional but often worth it
- Notes. A thank-you, delivery confirmation ("Final files sent Sep 8"), or the project name. Keeps the invoice human and self-explanatory.
- Late payment terms. A line like "Overdue invoices accrue 1.5% monthly interest" — only if your contract backs it up.
- Discount line. If you agreed to a discount, show it explicitly rather than silently lowering rates; it documents the concession and protects your rate card.
- Shipping/delivery charge. For physical goods, as its own line — never buried in item prices.
- Logo. Not required, but a branded invoice reads as established. See Adding Your Logo and Branding to Invoices.
What to leave off
Skip anything that adds clutter without helping payment: long legal boilerplate (that belongs in your contract), your life story, or multiple payment options with confusing instructions. And never include sensitive data you wouldn't want forwarded — an invoice gets passed around inside the client's company.
The checklist, filled in
Here's every essential field — plus a tax line, a PO number, and a discount — in one realistic invoice from an IT consultant to a clinic.
Example: complete consulting invoice with tax, PO number, and discount
All nine essentials in place, plus the conditional extras: GST line, client PO in the notes, and an itemized discount.
Run down the table above against this example and you can tick every row — which is exactly the exercise to do with your own invoice before sending.
Make the checklist automatic
The easiest way to never miss a field is to use a form that has a place for all of them. The free invoice generator includes every field on this checklist — line items, GST/VAT/Sales Tax at any rate, discounts, shipping, notes, and terms — and produces a watermark-free PDF in your browser with no signup. Fill it once, and the checklist takes care of itself.