German Invoices

How do I create a meaningful invoice number?

The most sensible invoice number is a consecutive numerical invoice number to keep track of the invoices in the outgoing ledger. You can find out in the article what the purpose of the outgoing invoice book is and why excessive creativity with invoic

Legal regulation of invoice numbers

Often you will find the answer in the law. Here: Sales Tax Act, namely Paragraph 14, the "Standard for issuing invoices". (

The fourth paragraph regulates what needs to be on an invoice. We have explained that in the article on the mandatory information on an invoice.

Sentence four defines the same invoice number: "(...) a consecutive number with one or more series of numbers that is issued once by the invoice issuer to identify the invoice (invoice number) (...)".
Let’s unravel this text.

Invoice number: simple and unique

Basically: creativity is beautiful, but should not necessarily be lived out with the invoice number. Especially when you write a lot of invoices, you can quickly get confused.

The simpler the invoice number, the better

It is best if you do not bother with the invoice numbers ( and you can easily keep track of them.

Tip: Keep your invoice number simple!

Start with number one. If you have two number ranges available, you could choose an even number series, i.e. 2,4,6, ... and an odd number, i.e. 1,3,5,...

Skip invoice number?

The good advice is 'no'. The number should be consecutive. Accordingly, you should avoid gaps and large jumps in the invoice number. Otherwise, you have to prove that you have not "deleted" an invoice and that you have all transactions in your bank account. If an incoming payment is not covered by an invoice, you can be accused of tax evasion.

In practice this has two advantages:

1. It's easy for the tax office and doesn't have to ask unnecessary questions
2. You don't have to explain yourself to the tax office.

Who wants to discuss this with the tax office?

Unique thing for the invoice numbers

Each invoice may only be issued once. Since the invoice number, as just learned, must be on the invoice according to the sales tax law, it can consequently only be unique.

The principle of uniqueness has top priority in jurisprudence.

And let's be honest, who doesn't want to be unique?

The thing with the outgoing invoice book

A long word: Invoice Output Book; is regulated in Section 238 of the Commercial Code (

Sorry, another legal passage. But according to this, “(...), every businessman (...) is obliged to keep books and to make his commercial transactions and the position of his assets evident in these according to the principles of proper bookkeeping. (...) ”

In short: You should list all your invoices and back them up with originals.

Important: The principles of archiving stipulate the retention obligation of invoices with a duration of 10 years.

Outgoing invoice book and invoice number?

In the outgoing invoice book, it is helpful, practical, and clear if you only use a consecutive invoice number.

You, your accountant, and the tax officer don't get mixed up. Good vibrations are always good. In addition, §238 HBG even defines that a third party must be able to look through your documents quickly.

If the check takes an eternity, i.e. an unreasonable amount of time, the tax office will recommend that you start over and ask unpleasant questions. You weren't trying to cheat something, did you? Unfortunately, a "no" answer is not enough.

Rule of thumb: Look at your accounting through the eyes of a tax officer.

What is a useful invoice number now?

Back to top. The little digression will certainly help you to answer the initial question better.
A reasonable invoice number is easy. There is no place for excessive creativity.
Still, in the end, you have to decide for yourself what makes sense.

For example, if you only have 5 customers and your program provides several number ranges, you could also use letters as a prefix.

Example of creative invoice numbers

For customer “apple” you could write AP-1 date. And for the customer “window”: FE-1 date.
* The main thing: * Don't get confused.