Invoice number rules in Germany: formats and examples
Short answer: German VAT law requires each invoice number to be unique and assigned in sequence. Letters, years and several separate number ranges are allowed, and gaps are not an error for VAT purposes. Small receipts up to €250 and, since 2025, invoices from small businesses under the Kleinunternehmer rule need no number at all, though using one is almost always wise.
Freelancers coming from the US are used to freedom here. Some number invoices by client initials and date, others let a payment tool generate random-looking IDs. In Germany, the invoice number is one of the mandatory details, and that makes people nervous. Myths spread fast: numbers must have no gaps, must restart at 1 every January, must not contain letters. None of that is in the law. The law has one half-sentence: a sequential number, made of one or more series, assigned once by the issuer to identify the invoice.
What § 14 UStG actually requires
Two things. The number must be unique, so no two of your invoices may share it. And it must be sequential, following a recognisable order. That is § 14(4) no. 4 UStG.
The Finance Ministry has spelled out the details in its VAT application decree. The key points:
- Numbers and letters may be combined.
- You may create as many separate number ranges as you like, for example per year, month, branch, project or client. Each invoice must clearly belong to one range.
- A gap-free sequence is not required.
- For long-term contracts that serve as the invoice, such as leases, one unique number for the contract is enough.
Unique means unique for you as issuer. Another business also having an invoice 2026-001 does not matter.
Which formats are allowed?
| Criterion | Allowed | Comment |
|---|---|---|
1047, 1048, 1049 | Simplest form, running sequence | |
2026-0001, 2026-0002 | Yearly range, restarts each year | |
INV-2026-10-007 | Monthly range with prefix | |
ACME-003 | Range per client, messy with many clients | |
BER-118, HAM-118 | Ranges per location, prefix makes them unique | |
2026-0007 used twice | Uniqueness broken | |
Date only, e.g. 14102026 | partly | Only if you never issue two invoices on one day |
Random code such as X7KQ2 | No recognisable sequence |
For most small businesses, a yearly range works best: 2026-001, 2026-002 and so on. It shows the year at a glance, helps with filing, and four digits cover up to 9,999 invoices a year. Prefixes such as „INV“ or the German „RE“ are a matter of taste. Using „S“ for cancellations keeps them neatly apart.
Are gaps allowed?
For VAT, yes. The decree says explicitly that a gap-free sequence is not required. Gaps can still become an issue elsewhere. In a tax audit, an examiner who sees jumps may ask whether income is missing. If you can explain them, such as a discarded draft or a software switch, there is no problem.
That leads to a practical rule. A sent invoice is never deleted, it is cancelled. The number stays used and the history stays traceable. How that works is in the article on how to cancel or correct an invoice.
Who needs no invoice number
Two groups. Receipts up to €250 including VAT need no number under § 33 UStDV, see small amount invoice. And since 2025, § 34a UStDV does not require one from small businesses under the Kleinunternehmer rule either, see Kleinunternehmer invoice.
Skip it only at a shop counter, though. Once a client pays „the invoice from Tuesday“ and you wrote three that day, you will see what the number is for. Many corporate accounts departments also reject invoices without a number, whatever the law says.
A numbering plan for a small studio
If you issue more than one type of document, set your ranges once and stick to them. An example for a design studio that sends deposit invoices, final invoices and the occasional cancellation:
| Document | Prefix | Example | Note |
|---|---|---|---|
| Standard invoice | INV | INV-2026-041 | One range per year |
| Deposit invoice | DEP | DEP-2026-012 | Own number per deposit |
| Final invoice | INV | INV-2026-042 | Lists every deposit |
| Cancellation | S | S-2026-003 | States the cancelled number |
Deposit and final invoices come with one more rule. Under § 14(5) UStG, the final invoice must deduct the deposits already received and the VAT on them, if invoices were issued for those deposits. The simplest way is to list each deposit invoice by number on the final one. Forget the deduction and you owe the VAT on the deposits twice, once from the deposit invoice and again from the final invoice.
Changing your numbering mid-year
Sometimes a switch cannot wait until January. You move to new software in May, or you realise in autumn that your old scheme was a mess. Changing is allowed. What matters is that both ranges stay unique and that nobody can confuse them.
The cleanest way is a new prefix. If your old invoices ran from 1 to 87, start the new tool at INV-2026-088 or at 2026-B-001. Write a short internal note on the date of the switch, the last old number and the first new one, and keep it with your records. Should an auditor ever ask about the jump, that note answers the question in one line.
What you must not do is renumber invoices that have already gone out. Their numbers are already in your clients’ bookkeeping.
Invoice numbers in e-invoices
In XRechnung and ZUGFeRD, the invoice number is a mandatory field labelled BT-1. The formats check that it is present, not that it is sequential. When you move from Word templates to invoicing software, continue your existing range rather than starting again at 1. With yearly ranges, New Year is the ideal moment to switch, since a new range starts anyway. More on what else changes is in e-invoicing in Germany.
Several tools, one numbering logic
Trouble starts when invoices come from several places: the online shop, the payment provider, the invoicing tool and now and then a Word file. Each counts on its own, and suddenly 2026-0042 exists twice. Separate prefixes per system, such as SHOP- and INV-, solve it. Every number is unique again and clearly belongs to one range.
Put the invoice number in the payment reference too. Ask clients to quote it, or print a payment QR code with the number pre-filled. Matching twenty incoming payments of €595 without a reference is guesswork.
If you generate invoices from your own platform, build numbering centrally and transaction-safe, so two simultaneous orders never get the same number. OnlineBuilders develops billing services like this for SaaS products.
Finally, audit your own practice. Take your last twenty invoices and check that each number appears once and that any gaps are explainable. For the other mandatory details, use the invoice checker.
Check an invoice for mandatory details: Tick what your invoice contains.
Questions people ask
Can my first invoice start at a number higher than 1?
Yes. The law sets no starting number. Starting at 1000 or 2026-100, so clients do not see it is your first invoice, is fine as long as the sequence continues from there.
Do I have to restart numbering every year?
No, but you may. A yearly range such as 2026-001 is allowed because the year makes each number unique. A single running sequence over several years is just as valid.
What if I used the same number twice?
Then one of the two invoices breaks the uniqueness rule, which can cause trouble with your client's input VAT. Correct the affected invoice with a document that assigns it a new, unused number and clearly refers to the original.
Are invoice numbers from Stripe or other payment tools valid?
Generally yes, as long as they follow a unique sequence. Problems arise when you issue invoices from two tools that both count independently. Separate prefixes per tool keep every number unique.
