Certificazione Unica
Also known as: CU, CUD, withholding certificate
The Certificazione Unica (CU) is the annual certificate an Italian client acting as sostituto d'imposta issues for what it paid you: the gross sums, the ritenuta withheld, the deductions applied and the social-security contributions. Art. 4 of DPR 322/1998 requires it to be handed to the recipient by 16 March and also filed with the Agenzia delle Entrate.1
What this means for you
It is the proof of tax already withheld on your invoices, and the figures your Redditi PF has to match. A forfettario usually receives none — those invoices carry no ritenuta, so there is nothing to certify. One 2026 change is worth a diary note: a CU carrying only self-employed professional income now reaches the Agenzia by 30 April, while your own copy is still due by 16 March.
Sources
Every figure on this page is grounded in primary sources — the same standard as the TaxCompass chat. This is sourced orientation, not tax advice.