Italy's SDI: How the First EU E-Invoicing Mandate Reduced its VAT Gap by Billions

On 1 January 2019, Italy became the first EU Member State to mandate electronic invoicing for all B2B and B2C domestic transactions — a bold move that was met with scepticism across Europe. The Sistema di Interscambio (SDI), operated by the Agenzia delle Entrate, became the central hub through which every invoice in Italy must pass.

The regulation was made possible by a special EU derogation from the VAT Directive (granted in December 2018), allowing Italy to require structured e-invoicing ahead of the EU-wide ViDA directive. Italy's argument was clear: with a VAT gap exceeding €35 billion in the mid-2010s, drastic measures were needed.

From day one, the SDI processed invoices in FatturaPA XML format, a structured standard that eliminates ambiguity. Every invoice receives a unique identifier, is validated in real-time, and is delivered to the recipient through the SDI platform. Non-compliant invoices are simply rejected.

According to the European Commission VAT Gap Report 2025 (published December 2025), Italy's VAT compliance gap decreased from 19.3% in 2019 to 15.0% in 2023. In absolute terms, this represents billions recovered:

The compliance gap measured at €25 billion in 2023 — still the 22nd worst in the EU. But the trajectory matters: before mandatory e-invoicing, Italy's gap consistently exceeded 25%, peaking above 30% in certain years. The SDI mandate has been the single largest contributor to closing this gap.

For context, Romania — which lacked mandatory CTC e-invoicing during this period — saw its gap remain at 30.0%, the worst in the EU. Meanwhile, countries that embraced digital reporting early, like Hungary (with its RTIR system), reduced their gap from 10.4% to 7.4%.

The Sistema di Interscambio (SDI) operates as a centralised clearance model — what the industry calls Continuous Transaction Controls (CTC). Here's the flow:

Since 2019, the SDI has processed over 2.7 billion e-invoices. In 2023 alone, the system handled approximately 2.1 billion structured transactions — making it the largest CTC e-invoicing system in Europe by volume.

Italy's SDI experiment has fundamentally shaped the EU's regulatory roadmap. The ViDA (VAT in the Digital Age) directive — which will mandate structured e-invoicing across all 27 EU Member States — was heavily influenced by Italy's success.

Now every major EU country is following Italy's lead: France (September 2026 for large companies), Germany (January 2027 for B2B receiving), Spain (2027 via Verifactu), Belgium (already live with Peppol), and Poland (KSeF mandatory from February 2026).

Italy's SDI success story isn't just an Italian story — it's a preview of what's coming to every European market. If your business operates across borders, the question isn't whether you'll need CTC-compliant e-invoicing, but how quickly you can implement it.

InvoStaq's AI-powered compliance platform already supports real-time CTC integration across 8 regulated markets — from Italy's SDI to Belgium's Peppol, Spain's Verifactu, Germany's XRechnung, Poland's KSeF, and the UAE's ZATCA. One integration, one API, every format.