When discussing the Italian ZES 2026 Tax Credit, most businesses focus on the eligibility requirements, qualifying expenditures and the amount of tax credit that may be obtained.
However, one often overlooked aspect could become highly relevant during a future tax audit: the wording used in invoices.
An invoice that is perfectly acceptable from a commercial perspective may not provide enough detail to allow the tax authorities to identify the asset purchased or the service provided.
Referring to a Contract Is Not a Substitute for Describing the Transaction
The Italian Supreme Court (Corte di Cassazione) has recently reaffirmed a well-established principle regarding invoices containing generic descriptions.
According to the Court, descriptions such as:
- “Final payment as per construction contract”;
- “Completion of works as per contract”;
- “Advance payment as per quotation”;
- “Services rendered as agreed”;
do not, by themselves, adequately identify the nature, quality and extent of the transaction being invoiced.
Article 21 of Presidential Decree No. 633/1972 requires invoices to contain sufficient information to identify the goods supplied or services rendered.
The Supreme Court has repeatedly held that an invoice constitutes valid evidence in favour of the taxpayer only when it complies with both the formal and substantive requirements established by law and clearly identifies the underlying transaction.
Among the most recent decisions are Supreme Court rulings No. 13806/2026, No. 2929/2026 and No. 3225/2025, which follow the same approach adopted in earlier decisions such as No. 9912/2020 and No. 14296/2021.
Particularly noteworthy is Decision No. 11911/2026, where the Court confirmed the non-deductibility of costs supported by invoices containing only the descriptions “completion of works as per construction contract” and “final payment as per construction contract”.
According to the judges, the existence of a valid and clearly identifiable contract does not eliminate the obligation to properly describe the transaction within the invoice itself. Contracts and invoices serve different purposes and cannot be treated as interchangeable documents.
Why This Matters for ZES 2026 Investments
The above decisions concern tax deductibility and VAT recovery.
However, the underlying principle is equally relevant to investments benefiting from tax incentives, including the ZES 2026 Tax Credit.
The tax authorities must be able to verify, even several years after the investment has been completed, that a particular invoice relates to a specific eligible investment.
During an audit, it should be possible to determine:
- which asset was purchased;
- which plant or equipment was installed;
- which construction works were performed;
- how the expenditure relates to the incentivised investment.
The more generic the invoice description, the greater the need to reconstruct the transaction through external documentation.
The Limits of Referring to External Documentation
In practice, invoices frequently refer to:
- quotations;
- commercial offers;
- technical specifications;
- bills of quantities;
- purchase orders;
- contracts.
These documents are undoubtedly important and often essential for documenting the investment.
However, such documents do not normally pass through the Italian electronic invoicing system (SDI) and may not be immediately available to a tax auditor reviewing the incentive several years later.
For this reason, businesses should avoid invoice descriptions that merely refer to external documentation without allowing the transaction to be identified directly from the invoice itself.
This does not mean that contracts, quotations or technical documentation should not be retained. On the contrary, they remain essential supporting evidence. Nevertheless, the invoice should maintain its own informational value.
Examples of Descriptions to Avoid and Preferred Alternatives
A description such as:
“Final payment as per contract dated 15 September 2026”
or:
“Advance payment as per quotation No. 34/2026”
provides very limited information about the actual nature of the transaction.
A more appropriate description would be:
“Final payment for the installation of electrical and auxiliary systems relating to the expansion of the production facility located in Catania”
or:
“Supply and installation of an automated packaging line intended to increase the production capacity of the facility”
In this way, the invoice allows the investment to be identified immediately without requiring access to additional documentation.
Practical Considerations
In most cases, there is no need to make every advance invoice highly detailed.
A reasonable approach is to issue advance invoices following normal commercial practice while ensuring that the final invoice contains a sufficiently detailed description of the works performed, equipment supplied or systems installed.
This approach strikes a balance between operational efficiency and documentary robustness.
Examples of Invoice Descriptions for ZES 2026 Investments
Descriptions to Avoid
- Advance payment as per quotation No. 15/2026
- Final payment as per contract
- Supply as per commercial offer
- Construction works as per technical specifications
- Professional services as per engagement letter
Preferred Descriptions
- Advance payment for the supply and installation of a photovoltaic system serving the production facility located in Catania
- Final payment for the expansion of an industrial building, including the construction of a steel structure and related works
- Supply of an automated packaging line intended to increase the production capacity of the facility
- Installation of electrical systems and distribution panels serving the new production area
- Engineering, design and construction supervision services relating to the expansion of the production facility
Conclusion
The ZES 2026 rules do not currently prescribe any mandatory wording for invoice descriptions.
Nevertheless, recent Supreme Court decisions confirm the importance of ensuring that invoices are capable of independently identifying the underlying economic transaction.
Since audits relating to tax credits may occur several years after the investment has been completed, businesses, suppliers and professional advisers should pay particular attention to the quality and detail of invoice descriptions.
Spending a few extra seconds drafting a more precise invoice today may significantly reduce the risk of future disputes with the tax authorities.