Invoice numbering in Billkeep

Setting the format

Settings → Your business. Each document type has its own sequence and its own settings:

Prefix — INV-, 2026/, your initials, or nothing at all.
Digits — how many the counter is padded to. Four gives 0042.
Restart — never, or every year. A yearly restart is what most accountants expect and what many jurisdictions want.

Invoices, quotes and credit notes number independently, so a quote never eats an invoice number.

When a number is taken

At the moment you press Finish invoice, and never before. This is why drafts show “not numbered yet” — an abandoned draft costs nothing, and a draft you started by accident does not leave a hole in your sequence.

The number is claimed in a single step that cannot be interrupted halfway, so two documents finished in the same second cannot take the same one.

Why documents cannot be deleted

Once a number is spent, the document can be cancelled but not deleted. Cancelling keeps the record and the number, and stops it counting anywhere.

A missing number in a sequence is exactly what an audit asks about, and “I deleted it” is a poor answer. A cancelled document is a normal, explainable thing.

Correcting keeps the number

Unlock to edit reopens a finished document. Fix it, finish it again, and it keeps both its original number and its original issue date — it does not jump to today's date or take the next number in the sequence.

Two devices

This is the genuinely hard part, and it is worth understanding. Gapless numbering works because one counter decides. Two devices working offline would both take 0007, and duplicate invoice numbers go badly in a tax audit.

So the number is claimed against your account: Billkeep reads the counter, writes the next value back with a condition that it has not moved since, and retries if the other device got there first. Two devices cannot take the same number.

That is why finishing a document needs a connection. Drafting never does — write as much as you like with no signal, and press finish when you have one. Guessing a number offline while your records are shared is exactly how two invoices end up with the same one, and no amount of tidying afterwards undoes a number that is already on somebody's paperwork.

The honest limit

You cannot have all three of offline finishing, several devices, and gapless numbering. Something has to give. Billkeep's answer is that drafting stays fully offline on every device, and claiming a number needs a connection when your records are shared. If you only use one device, none of this affects you.

Starting mid-sequence

Moving over from another system and already at invoice 214? Set the prefix and digits to match, and the counter carries on from where your records leave off, so your numbering does not restart in the middle of a tax year.

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