For companies operating in Italy that manage employees, collaborators, or external professionals, the Certificazione Unica (CU) represents a central tax obligation. This annual income certification is often perceived as complex. It is a formal document and a tool tax authorities use to calculate income, withholding tax, and contributions paid during the year.

In this article, we analyze the CU from the perspective of businesses in Italy. We explain what it is, its purpose, who must issue it, the data it must include, deadlines and penalties for noncompliance, and how it differs from other tax returns, such as Form 770 or income tax returns.

What’s in this article?

• What is the Certificazione Unica (CU), and what is it for?
  
• Who must file the CU?
  
• What data does the CU include?
  
• What are the deadlines for submitting the CU?
  
• What are the penalties for failing to submit the CU?
  
• Differences from other declarations: Form 770 and income tax returns
  
• Practical challenges for small and medium-sized enterprises (SMEs) and startups
  
• How Stripe can help companies with the CU
  

What is the Certificazione Unica (CU), and what is it for?

The CU is a tax document that a company or entity issues each year to certify the compensation and income paid to employees, collaborators, and professionals. It also indicates the taxes withheld. It is similar to a W-2 tax form in the US. In the past, the CU was known as the Certificazione Unica dei Redditi di Lavoro Dipendente (CUD). However, with the evolution of the tax return system, it is now simply known as the CU. This is because it now combines information into a single form that was previously fragmented.

For companies, the CU has a dual function:

• Allows the recipient (e.g., employee, collaborator, professional) to have an official overview of their income, which is useful for their tax returns
  
• Allows the tax authorities to cross-check the data reported by companies with that declared by taxpayers, thus reinforcing controls and the transparency of the system
  

When a business pays compensation subject to withholding tax (i.e., an advance tax deduction from the compensation), the business acts as a withholding agent. It withholds part of the compensation, pays it to the government, and certifies the transaction via the CU. This applies to income from employment, many forms of self-employment, and similar work.

Who must file the CU?

The obligation to file the CU applies to all businesses that paid compensation or income subject to withholding tax during the previous year. In other words, if a business paid employees, collaborators, or external professionals with amounts subject to withholding tax, it is required to prepare and submit the CU.

Those subject to this obligation include the following:

• Sole proprietorships, partnerships, and corporations
  
• Startups and SMEs, regardless of turnover or number of employees
  
• Professionals and associated firms that make payments to third parties
  
• Noncommercial entities and associations, when paying taxable compensation
  

The obligation is not contingent on the presence of employees. Businesses that work solely with external collaborators registered for value-added tax (VAT) must issue the CU. Furthermore, the CU is also required in certain cases where the tax withheld is zero, if the legislation still requires certification of the income paid.

Do those operating under the flat-rate regime have to issue a CU?

If a business operates under the flat-rate regime, it does not have to issue the CU for payments received. Professionals and entrepreneurs under the flat-rate regime are not subject to withholding tax and declare their income directly in their tax returns, according to the rules of the tax-relief regime.

Similarly, those who pay a professional under the flat-rate regime do not have to include those payments in the CU. This is because they are not subject to withholding tax. The CU remains mandatory for payments subject to withholding tax.

What data does the CU include?

One of the most delicate aspects of the CU concerns the quantity and quality of the data to be included. The CU indicates a total amount and provides a detailed breakdown that must be consistent with the company’s accounting records.

The main information included in the CU includes the following:

• Employee personal details, such as first name, last name, date of birth, and tax code
  
• Information on withholding agents (e.g., employers, pension bodies, and other entities that pay income) who are responsible for collecting and paying taxes on behalf of employees
  
• Type of income (e.g., employment, self-employment, other income, commissions)
  
• Amount of payments or income paid
  
• Withholding tax applied and paid
  
• Social security and welfare contributions paid
  
• Any regional and municipal surcharges
  
• Data relating to adjustments, deductions, and tax bonuses
  

What are the deadlines for submitting the CU?

In 2026, compliance with deadlines related to the CU is key to avoiding penalties and issues with the tax authorities. The CU relating to payments and income received in 2025 must be sent online to the Italian Revenue Agency by March 16, 2026 and delivered by the same date to employees, collaborators, or professionals who have received payments.

However, there is a differentiated deadline for certain types of certifications. CUs containing only income derived from self-employment in the normal course of business or profession—as well as nonoccasional commissions related to agency, brokerage, commercial representation, and business procurement—can be submitted by April 30, 2026.

What are the penalties for failing to submit the CU?

When the CU is sent after the deadline or contains incorrect data, Italian law provides for the application of specific administrative penalties. Circular No. 12/E of 2024 of the Italian Revenue Agency states that in the event of incorrect, late, or omitted submission of each certification, a basic penalty of €100 will be applied for each incorrect certification. This penalty can be up to €50,000 per year for each company that fails to comply with its declaration obligations.

However, there are some exceptions when calculating penalties:

• No penalty if the business submits the correct CU within five days of the date of rejection of the previous submission
  
• Penalty reduced to one-third (i.e., approximately €33.33 per certificate) with a maximum of €20,000 per year if the CU is correctly submitted within 60 days of the original deadline
  

In the same circular, the Italian Revenue Agency states that it is possible to benefit from the reductions in penalties provided for by the rules on voluntary correction.

Differences from other declarations: Form 770 and income tax returns

There are differences among the CU, Form 770, and income tax returns. Although they are related tools, they have different purposes and recipients.

A company issues and transmits the CU to certify the income and withholding tax of each recipient. On the other hand, a company submits Form 770 to inform the Italian Revenue Agency of the total amount of taxes withheld on payments made during the year and subsequently paid to the state, as well as other tax information related to these payments.

Meanwhile, the recipient files their income tax returns using the information provided in the CU to correctly report their tax position. In this sense, the CU represents a link between the company’s accounts and the personal taxation of employees and collaborators.

Practical challenges for small and medium-sized enterprises (SMEs) and startups

For many Italian SMEs and startups, managing the CU is a tax requirement and a major organizational challenge. Internal resources are often limited; processes are not fully structured; and rapid growth can further complicate the situation.

Here are some of the most common difficulties:

• Managing multiple types of collaborators (e.g., employees, freelancers, consultants)
  
• Correctly applying withholding tax on a contractual basis
  
• Reconciling invoices, payments, and tax data
  
• Consistently updating according to regulatory changes
  

In contexts where payments are made frequently or digitally, the risk of manual error is greater. This is why more and more companies search for solutions that allow them to centralize data, reduce repetitive tasks, and maintain a high level of control.

How Stripe can help companies with the CU

For Italian companies, one of the main difficulties in managing the CU is the collection of consistent and verifiable data on compensation, payments, and withholding tax. This is where Stripe’s solutions can offer concrete support, simplifying the processes upstream of CU completion.

With Stripe Invoicing, you can issue and manage invoices in a structured way, keeping invoiced amounts, collected amounts, and tax information associated with payment aligned. Because of collaboration with third-party partners, you can also use Invoicing for mandatory electronic invoicing.

Stripe Tax provides an automated solution for calculating the applicable VAT on transactions, taking into account local and cross-border tax rules. Although VAT does not constitute certified income in the CU, having accurate tax data tracked at the individual transaction level contributes to more reliable overall reporting that is easily verifiable in accounting terms.

Lastly, Stripe’s reports provide detailed and reconciled exports on payments, refunds, fees, and cash flows. These reports can be used to accurately record payments made during the year and to provide the accountant with structured data ready for completion of the CU and related forms. For SMEs and startups, this means fewer manual tasks, greater control over data, and a significant reduction in the risk of errors during the tax return phase.