Invoice numbering guide

Keep numbers unique

Use a sequence that lets you identify each invoice without accidentally reusing a number. For example: INV-2026-001, INV-2026-002 and so on.

Choose a system you can maintain

A simple sequential series is often easier for a small business than a complicated code. If you have multiple branches or business units, a prefix can make the source clearer.

Don't change numbers casually

Once an invoice has been issued, maintain a clear record of what happened if you need to correct or cancel it. Your accounting and tax requirements may determine how corrections should be handled.