Important: This document is provided to the best of our knowledge and describes the technical system only. It does not constitute legal or tax advice. Merchants should consult their Steuerberater for questions specific to their business.
1. System Architecture
Tebi is a cloud-based POS and restaurant management system made up of three core components:
Tebi POS App — runs on the merchant's terminal (tablet/device) and is used to take orders, print receipts, and process payments.
Tebi Backend — a cloud service that processes every transaction, maintains the merchant's ledger, and enforces business logic (pricing, tax, corrections, refunds).
Fiscalization layer — a dedicated service in the backend that intercepts every relevant transaction and routes it to Tebi's certified fiscal partner (see Section 3) before the receipt is finalized.
The POS app communicates with the backend over an encrypted connection. Each transaction is written to the merchant's ledger and, where fiscally relevant, published to an internal event stream that triggers fiscalization asynchronously, in real time.
2. Data Infrastructure
All transaction data is stored in Tebi's cloud ledger, hosted on infrastructure located in the EU. Each business transaction (order, payment, correction, refund) is recorded as an immutable ledger entry; corrections and refunds reference the original entry rather than altering it. Data is retained for the statutory retention period and can be exported by the merchant or the tax authority on request (see Section 3).
3. Data Immutability & Tamper-Proofing (TSE)
Since 2020, German law (§146a AO, KassenSichV) requires every POS system to secure its transactions with a certified Technische Sicherheitseinrichtung (TSE). Tebi meets this requirement using fiskaly's certified cloud-based TSE (SIGN DE V2) — no additional hardware is required on-site.
How it works:
Every transaction is sent to the TSE at start, on update, and on completion. On completion, the TSE returns a cryptographic signature and transaction number, which is printed on the receipt as a QR code.
These signed log entries are chained cryptographically, so any retroactive alteration is detectable. This chain — the TSS export (TAR file) — is the tamper-proof record of that a transaction occurred and was not manipulated. It can be exported on request (e.g. during an audit or Kassennachschau) independently of Tebi's own systems.
The itemized business data behind each transaction (line items, VAT, payment type) is exported separately in the standardized DSFinV-K format, which is what an auditor reads to understand what was sold; it relies on the TSS export to prove the data hasn't been tampered with.
Both exports (TSS TAR and DSFinV-K) are available to the merchant and, on request, to the tax authority, ensuring full traceability from the receipt back to the certified security module.