GoBD for tradespeople: the basics
Sequential numbers, immutability, retention — what the tax office expects from your invoices.
by Torsten Link · Last reviewed: July 10, 2026
The GoBD (principles for the proper keeping and retention of books, records and documents in electronic form) are the German tax authority's rules for how digital records and books must be kept so the tax office recognises them. For trade businesses, four principles are decisive.
01How must invoice numbers be assigned under GoBD?
Invoice numbers must be assigned uniquely, sequentially and traceably. Each number may occur only once, and gaps in the sequence must be explainable. That's why number ranges belong in software that assigns them automatically and without duplicates — not in an Excel list where numbers can accidentally be overwritten or duplicated. This keeps invoicing fully traceable for an auditor at any time.
02What does 'immutable recording' of invoices mean?
Once an invoice has been issued, its content may no longer be changed. If something is wrong, the rule is not correction in the document but cancellation and a new invoice. On the software side, an immutable recording (Festschreibung) ensures changes are technically ruled out — for example via a hash chain that would make any later manipulation visible. For you that means: you don't have to watch out that nothing gets changed — the system prevents it.
03How long must digital documents be retained?
Accounting documents such as invoices must be retained for eight years, commercial books and annual financial statements for ten. Retention may be fully digital, as long as the documents remain unchangeable, legible and quickly findable throughout the period. Simply filing a PDF in a folder is not necessarily enough — what's needed is a system that stores the documents in an audit-proof way and provides them immediately on request.
04What does traceability mean under GoBD?
Traceability means an auditor can follow every transaction seamlessly from quote through invoice to booking. Each step must be documented and linked to the next. An end-to-end system in which quote, job, invoice and accounting are connected delivers this thread automatically — instead of you having to manually gather documents from several programs and folders.
05What does the tax office check in an audit?
The auditor wants to verify that your records are complete, unalterable and well-ordered. This includes GoBD data access in three levels: direct access to your system (Z1), indirect access via reports (Z2), or handing over the data on a storage medium (Z3). A process documentation is also required, describing how records are created, booked and archived at your business. Those who work cleanly and completely in digital form face the least effort here — which is exactly the point of the GoBD.
- Assign invoice numbers with no gaps and no duplicates — sequential, but don't invent numbers after the fact.
- Write records immutably; later changes only as a traceable correction, never by overwriting.
- Keep booking documents such as invoices for 8 years in their original format — including incoming e-invoices and their emails.
- Maintain a process documentation: how records are captured, booked and archived.
- Keep data machine-analyzable at all times and ready for the tax audit's GoBD data access.
The short version
GoBD means: unique numbers, no changes after the fact, long retention, a clear audit trail. Good software handles this in the background — you just set it up right once.
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