What is an invoice number

All invoices and bills must have a unique and verifiable invoice number that identifies them.

The Australian accounting standards dictate that sales documents are to be sequentially pre-numbered using machine assignment or be distinctly marked in a manner that allows for complete and effortless verifiability of all issued sales transactions.

The Imperative of Sequential Invoice Numbering

For effective financial management and auditing, each invoice dispatched must carry a distinctive number in a continuous series. This sequence can commence with any number the issuer finds suitable, but it must progress in an unbroken numerical fashion for successive invoices. Common starting points range from ‘1’ to ‘1001’, followed by each subsequent invoice taking the next numerical value in sequence.

When transitioning to a new invoicing software, it’s crucial that the first invoice issued on the new platform picks up the sequence from the last number utilised in the former system. For example, should the last invoice be labelled ‘1089’, the following invoice should be marked as ‘1090’.

Since a seamless numerical progression is mandated, the cancellation or amendment of an already issued invoice is prohibited. Should an invoice contain inaccuracies, the correction process involves the issuance of a credit note.

Use an approved invoicing program

The invoice number must be either machine-generated or pre-printed to be valid. The easiest way to ensure that it is correct is to use an approved invoicing program.

In an invoicing program like Conta, the invoice number is automatically generated every time you create an invoice or credit note, so you don’t have to worry about if your invoices comply with the rules and meet all requirements.

Create free invoices with Conta

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Invoicing Outside of Software Solutions

Regarding using invoice templates or personally crafted invoices in software like Word, such practices are not permissible under Australian law. The flexibility to alter invoices post-issuance and the absence of sequential pre-numbering contravene regulations.

The only allowable alternative to invoicing software is the use of pre-numbered physical invoice forms, an approach reminiscent of traditional accounting practices. This historical method complies with the stringent requirements of sequential numbering, thereby preserving the integrity of accounting records.