Invoice Generator

The fields that make an invoice enforceable

An invoice needs a unique sequential number, an issue date, your legal name and address, the client's legal name and address, a clear description of what was supplied, the amount, the tax treatment and the payment terms. Missing any of these gives an accounts payable department a legitimate reason to return it, and the clock on your payment restarts from the corrected version rather than the original.

Sequential numbering is not decorative

Most tax authorities require invoice numbers to be unique and sequential with no gaps, because gaps suggest deleted invoices and unreported income. Starting at INV-1001 rather than INV-1 is a common cosmetic choice and is fine; skipping numbers because an invoice was cancelled is not. Cancel by issuing a credit note against the original, keeping the sequence intact.

Payment terms decide when you get paid

"Net 30" means 30 days from the invoice date, and it is the default many clients will apply whether or not you asked for it. Writing "due on receipt" without a date is weaker than a specific due date, because a specific date is what a payables system schedules against. Adding a stated late fee, where local law permits it, measurably improves payment times even when it is never charged.

Purchase order numbers

Larger organisations will not pay an invoice without a matching PO number, and their system rejects it automatically before a human sees it. If your client's process uses POs, the number belongs on the invoice, and its absence is the single most common cause of a mysteriously unpaid invoice from an otherwise reliable client.

Tax treatment must be explicit

State the tax rate, the tax amount and your tax registration number where you have one. For cross-border business-to-business supplies within the EU, a reverse-charge invoice must say so explicitly and carry both VAT numbers. "Tax not applicable" with no explanation is what triggers a query.

Send it as PDF, not a document file

A PDF renders identically everywhere and cannot be accidentally edited in transit. A word-processor file may reflow, may display differently on the recipient's system, and looks less finished. Name the file with your business name, the invoice number and the client, since it will sit in a folder with a hundred others called invoice.pdf.

Keep your copy

Retention requirements are typically five to seven years depending on jurisdiction. A generator that runs in the browser produces the document but does not archive it, so saving your own copy at the moment of issue is part of the process, not an afterthought.