What the law requires
§ 14 UStG asks for a „fortlaufende Nummer“ – a sequential number, made up of one or more series of figures, assigned once. That is the entire requirement.
Two myths follow from misreading it:
- „It must have no gaps.“ It must not. Cancelled or discarded numbers may be missing, as long as you can explain why.
- „It must be digits only.“ It must not. Letters are explicitly allowed.
Schemes that work
| Scheme | Example | Good for |
|---|---|---|
| Year plus counter | 2026-0001 |
The default. You see the year at a glance and restart each January. |
| Continuous | 1482 |
No year boundary, least thinking – but the number tells you nothing. |
| Year, month, counter | 2026-08-014 |
Monthly billing and quick lookup in a folder. |
| Prefix by document type | RE-2026-0147 |
Keeping invoices, quotes and credit notes apart. |
The one that goes wrong
If you switch systems, look up where the old one stopped and set the new one accordingly. Five minutes, once.
Customer-specific numbering
Several parallel series – one per customer, per project, per branch – are allowed, as long as
each individual number is assigned only once overall. In practice a prefix keeps that honest:
MEY-2026-004 and BER-2026-004 are two different numbers.
What about quotes and credit notes?
- Quotes need no sequential number – they are not invoices.
- Cancellation invoices follow the same rule as invoices: they get their own new number and reference the original.
- The word „Gutschrift“ has a specific legal meaning in German – it means the customer issues the invoice. Do not use it for a correction; it can create a VAT liability. Say „Stornorechnung“ or „Rechnungskorrektur“.
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Write an invoice – freeCommon questions
Can I restart at 1 every January?
Yes. Adding the year to the number keeps it unique overall, which is what matters.
Can I use the date as the invoice number?
Only if you never issue two invoices on the same day – otherwise the number is not unique. Adding a counter fixes it: 20260814-01.
What if I notice a duplicate number afterwards?
Correct it, document what happened, and keep both documents. An explained mistake is a very different thing from an unexplained gap in the records.
Do private individuals issuing an occasional invoice need one?
The sequential-number requirement follows from VAT law and applies to businesses. A one-off private invoice is a different situation – but numbering it costs nothing.
Legal basis
This page refers to the following German provisions so you can look them up yourself. It is information, not legal advice for your individual case.
- § 14 UStG – issuing invoices and mandatory content (German VAT Act)
- § 19 UStG – small business rule
- Directive 2014/55/EU – European standard EN 16931 for electronic invoicing