Invoice numbers: gapless and sequential

Overview

Invoice numbers must be sequential and unique (Section 14 of the German VAT Act) – gaps raise uncomfortable questions during tax audits. Kyvento therefore assigns numbers automatically via configurable number ranges and ensures gaplessness technically. This article shows the settings and explains the mechanics.

Configuring number ranges

Under Settings → "Number ranges" you see all document types with their format, next number and annual reset. Each document type has its own range – including:

• Invoice: default format RE-2026-00001 (year + five-digit counter, annual reset)
• Cancellation: its own range with the prefix ST-
• Customer and Product: sequential without a year (K-00001, P-00001)
• Quote and Order confirmation: AG- and AB- respectively, with a year

The format, next number and annual reset can be adjusted per range – ideally once before you start, so that the series stays consistent. Kyvento prevents turning the next number back, because numbers already assigned must never be created again.

How Kyvento guarantees gaplessness

• Number only at finalization: drafts carry no invoice number. Only at finalization does Kyvento draw the next number – so a discarded draft leaves no gap.
• Assignment within the transaction: the number is assigned exclusively within the finalization operation. If the operation fails, the counter is rolled back as well – the number is not lost.
• Collision protection: even when several invoices are finalized at the same time (for example in the nightly billing run), neither duplicates nor jumps occur.
• Chronology: the year in the number follows the invoice's document date – the series stays consistent even around the turn of the year.

Cancellations and dunning notices

A cancellation never changes the original's number: the cancellation document receives its own number from the cancellation range, and the original remains unchanged. Dunning letters and payment reminders deliberately receive no invoice number – they are not invoices within the meaning of Section 14 of the German VAT Act.

Good to know

• Number ranges apply per Kyvento account – if you run several accounts, each keeps its own series.
• With the annual reset, the counter starts again at 1 in the new year; thanks to the year in the format, the numbers still stay unique.
• Gaplessness per year is checked by the system – together with the checksums from "GoBD-compliant archiving", the document chain is thus audit-proof.

Next steps

• What else happens during finalization – see "Automatic invoice creation"
• Immutability and retention – see "GoBD-compliant archiving"