Why your invoice numbers should never have gaps
The rule fits on one line. The cases around it are where numbering usually breaks.
Dutch invoicing rules ask every invoice to carry a unique number from a continuous series. You may run more than one series, one per year for example, as long as each series has no holes. A gap invites the question every bookkeeper dreads: what happened to the missing invoice?
Where gaps come from
Almost never from fraud. Usually from tools that hand out a number too early.
- Deleted drafts. A draft gets number 260011, you delete it, and the next invoice becomes 260012.
- Corrections. An invoice is edited after sending, so the number now points to two different documents.
- The new year. The series restarts in January, but some December invoices are only sent in January.
How gonibabki keeps the series whole
Numbers are given at sending, not at drafting
Drafts carry no number, so deleting one costs nothing. The number is reserved the moment you send, or mark the invoice as sent.
A deleted number becomes void, not a hole
If sending failed after a number was reserved and you delete that draft, it stays in the list as void when later numbers exist. The series stays readable from start to end.
Corrections keep their history
Reopening an invoice asks for a reason and stores a new PDF version under the same number. A credit invoice takes its own number and refers to the original.
One series per year
Numbers look like 260011: the year, then the sequence. The year follows the invoice date, so a December invoice sent in January still belongs to December's series.
This post is general information, not tax advice. Check your situation with your accountant.