CTC (continuous transaction controls) are tax rules that give the tax authority invoice data when a transaction happens, instead of in a later audit. There are three main models: reporting, centralized clearance, and decentralized CTC and exchange (DCTCE), often called the five-corner model.
The models in brief
| Model | What happens | Examples |
| Post-audit (no CTC) | Invoices go directly between the parties and are checked afterwards. | Sweden, Denmark, Germany |
| Reporting | The invoice goes to the buyer and invoice data is reported to the tax authority within a set time. | Hungary, Spain (SII) |
| Centralized clearance | The tax platform validates the invoice before it is delivered or counts as issued. | Italy, Poland, Saudi Arabia |
| DCTCE (five-corner model) | Certified service providers exchange the invoice and report tax data to the tax authority (C5). | UAE, Singapore, Slovakia |
The five-corner model and Peppol
In Peppol, the seller and buyer each use a service provider (C2 and C3). In OpenPeppol’s CTC model, the tax authority or its service provider is the fifth corner (C5), and C2 and C3 send it Tax Data Documents. The model is described in the Peppol CTC Reference Document, with country-specific specifications for the UAE, Slovakia, and Oman.
What changes in the EU
From 1 July 2030, ViDA requires digital reporting of cross-border B2B transactions within the EU, based on EN 16931 e-invoices. See What is ViDA?.
For a country-by-country status in 2026 and what CTC means for your business, read What is CTC? Continuous transaction controls and the five-corner model explained.