> ## Documentation Index
> Fetch the complete documentation index at: https://whalescorp.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Invoice Number Format

```text theme={null}
INV-{YEAR}-{SEQ:04d}     e.g. INV-2026-0042
```

Sequence counter stored in `instances.settings.invoice_seq`, incremented atomically per transaction.


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