Studio PonchioSTPFirm Guides · Electronic invoicing
Electronic invoicing: practical guide
Electronic invoicing is no longer a novelty: it is the standard way to document transactions in Italy. Yet it remains one of the areas where the most formal errors are made, with consequences ranging from rejection of the document to penalties. This guide explains how the system works, the types of documents, issuance deadlines, storage (conservazione) and related compliance requirements, with the practical details that make the difference.
Update note: the structural rules described here are well established. Items marked as “(to be confirmed)” depend on extensions or annual measures and must be checked against official sources before any application.
1. What it is and how the Sistema di Interscambio works
The electronic invoice is a file in XML format, compliant with the specifications of the Agenzia delle Entrate, transmitted through the Sistema di Interscambio (SdI), which works like a public “postman”: it receives the file from the supplier, checks its formal correctness and delivers it to the customer.
The workflow for each document is always the same:
- The supplier prepares the XML file and signs it or transmits it through its own intermediary or software.
- The SdI carries out the formal checks (existing VAT number (partita IVA), valid recipient code, consistency of the amounts, field format).
- If the checks fail, the SdI issues a rejection receipt: the invoice is considered not issued and must be retransmitted corrected within 5 days, keeping the original date and number.
- If the checks are passed, the SdI delivers the file and returns a delivery receipt (or a notice of impossibility of delivery, with deposit in the recipient’s reserved area).
Delivery takes place via the recipient code (7 characters) or the PEC notified by the customer. For customers without a VAT number (private consumers) the conventional code 0000000 is indicated and the customer is given a paper copy or a PDF copy, informing them that the original is available in their reserved area.
2. Who is required: the timeline
The obligation has been progressively extended until it became general:
| Effective date | Entities involved |
|---|---|
| 2014 | Transactions with the Public Administration |
| 1 January 2019 | Most VAT taxable persons, B2B and B2C transactions |
| 1 July 2022 | Flat-rate and “minimum” taxpayers with revenues or fees above 25,000 euros in the previous year |
| 1 January 2024 | All flat-rate taxpayers, with no exemption threshold any longer |
Entities not established in Italy and certain specific cases remain outside the obligation. It should be recalled the ban on issuing electronic invoices via SdI for healthcare services provided to private individuals, for reasons of protection of health data: such transactions are documented in paper form or in electronic form outside the SdI (the measure has been extended year by year: to be confirmed for 2026).
3. Document types (TD codes)
The field DocumentType qualifies the nature of the transaction and is one of the points where mistakes are most often made. The most frequently used codes:
| Code | Document | When it is used |
|---|---|---|
| TD01 | Invoice | Ordinary case of sale of goods or supply of services |
| TD02 | Deposit or advance on invoice | Advance payment compared to the transaction |
| TD04 | Credit note | Total or partial cancellation of an invoice |
| TD05 | Debit note | Upward adjustment (increase) to an invoice |
| TD06 | Fee invoice | Self-employment income |
| TD16 | Internal reverse charge integration | Purchases under reverse charge from Italian suppliers |
| TD17 | Integration or self-invoice for services from abroad | Purchase of services from EU and non-EU taxable persons |
| TD18 | Integration for intra-Community purchase of goods | Purchases of goods from EU suppliers |
| TD19 | Integration or self-invoice pursuant to art. 17 c. 2 | Purchase of goods from non-residents already present in Italy |
| TD20 | Self-invoice for regularization | Invoice not received or irregular from the supplier |
| TD24 | Deferred invoice | Supplies with DDT or documented services |
| TD27 | Self-consumption or free supplies | Allocation to purposes unrelated to the business |
4. Issuance deadlines
- Immediate invoice: must be transmitted to the SdI within 12 days from the date the transaction is carried out. The “Date” field in the file remains that of the transaction, not that of the transmission.
- Deferred invoice: for supplies accompanied by DDT or for documented services, it is issued by the 15th day of the following month after the month in which the transaction is carried out, with a summary of the month’s transactions.
Compliance with the deadline is essential: the transaction date determines when the tax becomes chargeable and therefore the VAT settlement in which the document is included.
5. Reverse charge, self-invoices and cross-border transactions
In the domestic reverse charge the supplier issues an invoice without VAT and the customer supplements the document with the rate and tax, recording it both in purchases and in sales: the supplement is transmitted to the SdI with code TD16.
For cross-border transactions the old esterometro has been superseded: the data are communicated through the SdI. In summary:
- Purchases from abroad: the supplement or self-invoice document is transmitted with TD17 (services), TD18 (intra-Community goods) or TD19 (goods from non-residents already in Italy), by the fifteenth day of the month following that of receipt of the document.
- Supplies to abroad: a standard electronic invoice is issued indicating as recipient code XXXXXXX (seven Xs) when the foreign customer does not have an SdI channel.
6. Stamp duty
On electronic invoices with no VAT charged of an amount exceeding 77.47 euros, stamp duty is due in the amount of 2 euros. This typically concerns flat-rate taxpayers (forfettari), as well as exempt, non-taxable, out-of-scope and excluded transactions. In the XML file, the specific field “Bollo virtuale” must be filled in.
Agenzia delle Entrate makes available, in the reserved area, the statement of the amounts due, calculated on the invoices transmitted. The payment is quarterly, with a simplification rule: if the amount due for the first quarter does not exceed a minimum threshold, the payment may be deferred and combined with subsequent quarters (thresholds and deadlines to be confirmed for 2026).
7. Statutory-compliant archiving
Electronic invoices must be archived in a statutory-compliant electronic manner for 10 years. Saving the XML files on a disk or in a folder is not sufficient: statutory-compliant archiving requires a process with a timestamp and a records-keeping manager (responsabile della conservazione), which ensures authenticity, integrity, readability and retrievability over time.
Agenzia delle Entrate offers the archiving service free of charge upon acceptance of the service agreement in the reserved area: it is a practical choice for small entities, provided that the acceptance is actually activated. Many taxpayers take archiving for granted because “the invoices are in the portal”: this is a frequent and risky misunderstanding.
8. Penalties
Failure to issue the electronic invoice (fattura elettronica), or issuing it late, is penalized proportionally to the tax not correctly documented, with a minimum for each transaction; if the violation does not affect the tax settlement (liquidazione dell’imposta) the penalty is fixed and reduced. The measures were revised by the reform of the penalty system (D.Lgs. 87/2024) for violations committed from 1 September 2024 (exact amounts to be confirmed).
In any case, violations can be regularized through voluntary disclosure (ravvedimento operoso), with reductions that are greater the more timely the corrective action. The most delicate case remains the rejected invoice (fattura scartata) and never retransmitted: for the tax authorities that invoice is deemed never to have been issued.
9. Frequent errors and best practices
- Ignoring the SdI (Sistema di Interscambio) receipts. They must be checked systematically: an invoice rejected and not retransmitted within 5 days becomes a case of omitted issuance.
- Using the wrong TipoDocumento code, in particular for integrations under reverse charge and for purchases from abroad.
- Incorrect or missing recipient code (codice destinatario): it causes rejections or failed delivery. It must be requested and verified when setting up the customer’s master data.
- Forgetting the stamp duty (bollo) on invoices without VAT above 77.47 euros: a typical mistake by flat-rate scheme taxpayers (regime forfettario).
- Confusing the transaction date with the sending date, with effects on the VAT settlement (liquidazione IVA).
- Not activating legally compliant archiving (conservazione a norma), believing that storing it in the portal is sufficient.
- Not providing the courtesy copy to the private customer, who often does not check the reserved area.
- Not regularizing with TD20 when the supplier does not issue the required invoice.
10. Two practical examples
Example 1 – Flat-rate scheme taxpayer (regime forfettario) invoicing an Italian company. A consultant under the flat-rate scheme issues an invoice for 1,500 euros. She uses the code TD06, does not charge VAT (indicating the transaction nature provided for the flat-rate scheme), does not apply withholding tax (ritenuta d’acconto) and, exceeding the amount of 77.47 euros, fills in the 2-euro stamp duty (bollo) . She transmits it within 12 days from the invoice date and checks the delivery receipt.
Example 2 – Purchase of a service from an EU supplier. An Italian company receives from a German supplier an invoice for consultancy services, without VAT. The company must integrate the document with Italian VAT and transmit to the SdI (Sistema di Interscambio, Italian e-invoicing platform) a file with code TD17 by the fifteenth day of the month following receipt, recording it both among purchases and among sales. Omitting this step means you have not fulfilled the communication of cross-border transactions.
In summary
E-invoicing rewards method: complete and verified customer master data, systematic checking of SdI receipts, attention to the document type, compliant archiving (conservazione a norma) that is actually active, and oversight of the stamp duty (bollo). These are simple measures that prevent almost all issues. Studio Ponchio is available to help set up the invoicing cycle, verify reverse-charge integrations, and manage compliant archiving.