Since January 1, 2019, electronic invoicing (fatturazione elettronica) via the Sistema di Interscambio (SdI) has been mandatory for all Italian B2B transactions, and since July 2022 it applies to most B2C transactions in hospitality too. For accommodation providers, this means every invoice — from a one-night stay to a corporate group booking — must be transmitted through SdI before it is legally valid.
This guide explains exactly how SdI works for hotels and vacation rentals, and how to automate it completely.
What is SdI?
The Sistema di Interscambio is Italien's government-operated e-invoicing infrastructure, managed by the Agenzia delle Entrate (Italian Revenue Agency). All electronic invoices must be transmitted through SdI in XML format (FatturaPA), receive a unique protocol number, and be stored for 10 years.
SdI acts as an intermediary: the issuer (your property) submits the XML invoice to SdI, which validates it and delivers it to the recipient's (guest's or company's) fiscal code or VAT number.
FatturaPA XML — What It Contains
Every SdI invoice must include:
| Field | Description |
|---|---|
| Codice Fiscale / P.IVA | Your property's Italian tax ID |
| SDI Recipient Code (Codice Destinatario) | 7-digit code for B2B, ZZZZZZZ for B2C |
| Progressive invoice number | Unique sequential per year |
| IVA rate and amount | Per line item |
| Service description | Accommodation, breakfast, extras |
| Payment method | Bonifico, cash, card |
| Transmission date | Must match or precede service date |
A PMS that generates FatturaPA XML automatically eliminates the most error-prone step in the SdI process.
The Submission Flow
- **Invoice created** in PMS at checkout or billing
- **FatturaPA XML generated** automatically by the PMS
- **Transmitted to SdI** via certified API connection
- **SdI validates** the XML (format, fiscal codes, IVA rates)
- **Protocol number assigned** (numero di protocollo) — receipt confirmation
- **Delivered to recipient** (guest email or company SDI code)
- **Stored in Nokumo archive** for mandatory 10-year retention
The entire process from invoice creation to protocol confirmation should take under 5 seconds in a properly integrated system.
Common SdI Errors and How to Avoid Them
**Error 00001 — Schema not valid:** XML structure error. Caused by manually edited invoices or outdated PMS versions. Solved by using a PMS that auto-generates valid FatturaPA.
**Error 00100 — Duplicate invoice number:** Sequential invoice numbers skipped or reused. A PMS manages sequential numbering automatically.
**Error 00404 — Fiscal code not found:** Guest's codice fiscale incorrect or not in Anagrafe Tributaria. For B2C invoices, using ZZZZZZZ as recipient code avoids this.
**Error 00500 — Service unavailable:** SdI system downtime. A PMS should queue invoices and retry automatically during SdI outages (which affect all providers equally).
B2C Guest Invoices — Scontrino vs Fattura
For individual guests (B2C), accommodation providers have two options: - **Scontrino fiscale (fiscal receipt):** Simpler, for guests who don't need an invoice for expense claims - **Fattura elettronica B2C:** Full SdI invoice, required if the guest provides their codice fiscale
Most hospitality PMS systems offer both at checkout. The guest is asked whether they need a formal fattura or a scontrino.
Automating SdI in Nokumo
Nokumo handles the complete SdI workflow without manual steps:
- Invoice created at checkout — IVA rates applied automatically (10% accommodation, 22% extras)
- FatturaPA XML generated and transmitted to SdI
- Protocol number received and stored against the reservation
- Guest receives invoice PDF by email
- Invoice stored in Nokumo's 10-year archive, searchable by date, guest, or protocol number
During SdI outages (rare, but documented), Nokumo queues invoices and retries automatically. No manual intervention required.
Penalties for Non-Compliance
The Agenzia delle Entrate issues penalties for SdI non-compliance: - **Late transmission (beyond 12 days):** €250–2,000 fine - **Incorrect IVA rate:** 90% of the IVA difference due - **Missing invoice:** 90–180% of IVA due, plus criminal exposure for repeated violations
For a property processing 1,000+ invoices per year, manual SdI processes create substantial compliance risk. Automation is not optional — it is the only practical path.