Invoice numbering
Invoice numbers are allocated by KAMI from a sequence you configure: a prefix, a running number, and zero-padding. In most jurisdictions the sequence itself is a compliance matter, not a formatting preference.
Where: Invoices › Settings You need: the invoicing settings right
What you configure
| Setting | Default | Decides |
|---|---|---|
| Prefix | INV | The text before the number |
| Next number | 1 | The next numeric suffix to allocate |
| Padding | 6 | Minimum digits, zero-padded |
With the defaults, the first invoice is INV000001.
Alongside these sits the reporting currency, which the receivables views roll up into — see Currencies and FX rates.
Why the sequence matters
Tax authorities in most jurisdictions expect invoice numbers to be sequential and without gaps, because a gap suggests an invoice was issued and then hidden. That is why the number is allocated at issue, not when a draft is created — drafts that are never issued do not consume numbers.
⚠️ Do not move the next number backwards. Reusing a number produces two different documents with the same identity, which is a real compliance problem and an unpleasant one to unpick with a client who holds both. Moving it forward creates a gap, which you may have to explain.
Set the prefix and padding once, before your first invoice, and leave them alone. Changing the prefix mid-year gives you two numbering schemes in the same tax year.
Continuing an existing sequence
If you are migrating from another system, set next number to continue where that system stopped, and match the prefix and padding if you can. The alternative is a visible discontinuity in your invoice register that someone will eventually ask about.
How to configure it
- Open Invoices › Settings.
- Set the prefix — short, and meaningful to your finance team.
- Set the padding to a width you will not outgrow.
- Set the next number, continuing from any previous system.
- Set the reporting currency.
- Issue one invoice and confirm the number is what you expect.
What Happens Next
- Numbers are allocated at issue and appear on the document.
- The next number advances automatically.
- Reissuing an invoice does not renumber it.
Tips
- Choose padding generously. Six digits costs nothing and avoids the day your numbers change width, which looks like a different scheme to anyone filing them.
- Do not encode the year in the prefix unless your accountant asks for it. It commits you to changing the prefix annually and to explaining the change.
- Check the sequence at year end for gaps, and be able to explain any you find.
- Never edit next number to fix a mistake. Correct the invoice; the number is the one thing that should not be adjusted.
- Agree the scheme with your accountant before the first invoice, not after a hundred.
Troubleshooting / FAQ
Q: An invoice has no number. Numbers are allocated at issue. A draft or unapproved invoice has none yet.
Q: There is a gap in our sequence. A number was allocated to an invoice that was later voided or reissued. Be able to explain it.
Q: Can we change the prefix? Technically yes; it gives you two schemes in one period. Check with your accountant first.
Q: Can two invoices share a number? They should never. If the next number was moved backwards, stop and reconcile before issuing anything further.
Q: We are migrating — how do we continue our old sequence? Set the next number to follow it, and match the prefix and padding.