The Italian Tax Agency has published the CU 2023 (Certificazione Unica) model form with the relevant instructions. 
The CU 2023, is a fundamental tax document required by pensioners, employees and the self-employed who are in receipt of income from an Italian employer, pension provider or who have Italian business clients. In general Italian businesses are required to make payment of salaries, pensions, or professional fees, subject to withholding of income tax.
For any business or pension provider making this kind of payment, the CU must be filed online with the Tax Agency by 16 March 2023, for CU’s covering income from employment, self-employment income, pension income and certain other types.
A copy of the CU must also be issued to the recipient of the income by the same date.
The CU is intended to summarise all amounts paid to the recipient during the course of the previous tax (calendar) year, such as:
- Income from employment, and income which under law is treated as or assimilated to income from employment (pension income, benefits in kind etc.);
- Income from self-employment which is subject to withholding tax on payment;
- Other income pursuant to art. 67, paragraph 1 of the Tax Code (other income/capital gains), subject to withholding;
- Payments for for services, including occasional services, relating to commission, agency, mediation, sales representation and business procurement activities;
- Payments deriving from activities of door to door selling;
- Certain payments made by a condominium, for services of supply or works and services;
- Payments due on the termination of an agency relationship with an self-employed agent;
- Payments for self-employed sporting activities;
- Sums paid following garnishment procedures at third parties and sums paid by way of expropriation indemnities, other indemnities and interest.
The CU 2023, is also used to certify social security contributions paid or due to INPS and certain other institutions.