The bad news first: many international SaaS vendors do not understand the German rules for proper bookkeeping. They ship clean software, beautiful UIs and impressive features – but they fail on topics like GoBD, DATEV export, POS-TSE or electronic invoicing. In the SME world this leads to two problems: duplicate work at the tax advisor and risk during tax audits.
This article explains what is behind the German requirements, why off-the-shelf SaaS often fails them, and how a custom solution maps these topics cleanly.
GoBD: the rules of German bookkeeping
GoBD stands for "principles for the proper management and storage of books, records and documents in electronic form, as well as for data access". Bulky, but central. The key requirements:
- Immutability: once posted, vouchers cannot be changed
- Completeness: all tax-relevant transactions must be recorded
- Traceability: every change must be logged (audit trail)
- Retention: 10 years, audit-proof
- Timeliness: business transactions must be booked promptly
- Data access: tax audits must be able to use Z1, Z2 or Z3 access
Most international SaaS vendors don't meet GoBD or only partially. This usually only becomes visible during the first tax audit – and then it gets expensive.
DATEV export: more than a CSV file
DATEV is by far the most widespread platform of German tax advisors. A real DATEV interface means much more than "CSV export":
DATEV format DTVF
A specific format for booking entries with accounts, cost centres, debit/credit, voucher numbers and posting texts. Column order is precisely defined. Wrong formatting causes import errors at the tax advisor.
SKR03 / SKR04 charts of accounts
Standard charts for German bookkeeping. Vouchers must be assigned to the right accounts automatically or manually – which presupposes that the software knows the chart and not just English categories like "Office Supplies".
VAT-ID check and reverse charge
For intra-EU deliveries the recipient's VAT ID must be checked. Reverse-charge cases must be booked correctly. Internationally designed software often doesn't know these specifics.
You don't recognise a real DATEV interface by the word "DATEV" on the website – but by whether the vendor can show concrete DATEV certifications or references from German tax advisors.
POS-TSE: mandatory since 2020
Anyone running an electronic POS system in Germany has to use a technical security device (TSE) since 2020. Without TSE there are fines up to €25,000 and, in repeated cases, the loss of the POS approval.
International SaaS POS systems often do not offer a TSE certified in Germany – some only as an expensive add-on. In a custom build the TSE integration is planned in from the start.
E-invoicing from 2025: mandatory for B2B
Since 1 January 2025 companies in Germany must be able to receive electronic invoices in B2B. By 2028 the obligation to send them will be phased in. The recognised formats are XRechnung and ZUGFeRD.
Many international SaaS tools still send only PDFs – that no longer meets the rule. Structured data in one of the two formats is mandatory. Anyone buying a SaaS today must check whether e-invoicing is properly supported.
Industry-specific interfaces
Beyond the general obligations there are industry standards that off-the-shelf SaaS often doesn't cover:
Trades and construction
- GAEB format for bills of quantities and measurements
- BAU-Steine: standardised text blocks from the ZDB
- Payroll with SOKA-Bau and minimum-wage obligations
Healthcare
- KIM (communication in medicine) for secure messaging
- Telematics infrastructure (TI) connection
- Special billing per EBM, GOÄ, BG
Legal
- beA (special electronic lawyer mailbox)
- Court-file-number logic
- RVG-compliant fee billing
Logistics and forwarding
- EDIFACT messages (IFTSTA, INVOIC, etc.)
- Connections to MES and ERP systems of large shippers
- Customs and ATLAS interfaces
How custom SaaS solves these topics
In a custom build, interfaces are not a sales pitch but part of the requirements analysis. We typically proceed like this:
- In the workshop we clarify together which external systems must be connected – and how deeply
- In the concept each interface is described individually: format, frequency, data flow, error handling
- In development the interfaces are built modularly so that they can be swapped or extended later
- In operations we actively monitor the interfaces – when the tax advisor reports a DATEV import error, we often see it before they call
Example: GAEB measurement in construction
A typical Klarspur project: a mid-sized civil-engineering firm wanted to digitalise its measurement capture. Standard construction software exists, but none offered a really clean GAEB connection to the architect software of the main client. The result: measurements were captured twice – once in the construction software, once converted manually into GAEB format.
The custom solution captures measurements directly in GAEB format, sends them automatically to the architect and hands them to the internal order management. Result: 6 hours of duplicate work saved per week, fewer transcription errors, happier site managers.
What to look for when buying off-the-shelf SaaS
Even if you go off-the-shelf, clarify these questions before signing:
- Is the software GoBD certified? Is there a German auditor's testimonial?
- Which DATEV interfaces are included? In which formats?
- Are SKR03 and SKR04 supported?
- Is VAT-ID checking integrated? Reverse charge?
- Is e-invoicing supported in XRechnung and/or ZUGFeRD – receiving AND sending?
- Where is data stored? Is there a DPA?
- Is a POS-TSE integrated (if relevant)?
Conclusion
The German obligations on bookkeeping, data retention and interfaces are not a detail – they are the point at which many off-the-shelf SaaS solutions either fail or require workarounds so complex that the efficiency gains are lost again. A custom build can map these topics cleanly from day one because it is designed from a German perspective.
Not sure whether your current SaaS is GoBD compliant and has all the interfaces you need? We check that for free in a 30-minute call – and tell you honestly whether action is needed.