00409: Duplicate invoice in the batch
What it means
SdI code 00409 means the batch file contains invoices that match under SdI's duplicate checks.
The usual cause
Check for repeated invoice numbers for the same seller and year, allowing a credit note (TD04) to share a number with a non-TD04 document. For invoices issued under Article 73 with Art73 set to SI, compare the full invoice date instead of only the year.
How to fix it
Remove any repeated invoice or correct a number that was reused by mistake, and send the batch again.
Elements the check reads
-
1.2.1.1 IdFiscaleIVA -
2.1.1.1 TipoDocumento -
2.1.1.3 Data -
2.1.1.4 Numero
The code as published
Read the official document . Source: Elenco dei controlli effettuati sul file fattura del Sistema di Interscambio, version 2.0, published by Agenzia delle Entrate, fatturapa.gov.it, read on 8 November 2026.
Klarbon explains each code in its own words; the official wording is in the document linked above.
Look at your file
Open the invoice in your browser to find the fields this code names: Open an Italian FatturaPA invoice. Open an Italian FatturaPA invoice