Unpaid business invoices: late-payment interest and useful documents

When the late-payment rules apply

Legislative Decree No. 231 of 9 October 2002 governs payments due as consideration in commercial transactions. Articles 1 and 2 cover contracts between businesses and between businesses and public authorities that predominantly involve supplying goods or services for a price. The definition of an entrepreneur also includes those practising a liberal profession.

These rules therefore do not apply indiscriminately to every unpaid debt: consumer transactions require a different legal assessment. The decree excludes, among other matters, debts covered by insolvency proceedings opened against the debtor and payments of compensation for damage. Before calculating amounts, the relationship must be classified and any special rules checked.

The due date does not always coincide with the invoice date

Article 4 links the ordinary payment periods, depending on the circumstances, to receipt of the invoice, delivery of goods, performance of services or the stipulated acceptance or verification procedure. Businesses may agree payment periods within the statutory limits. It is incorrect to assume that all invoices automatically fall due the same number of days after issue.

A properly prepared file also retains evidence of these dates. Orders, accepted terms, transport documents, delivery records and transmission receipts can clarify when performance took place and when the customer received the payment request. Any complaints about the conformity of the supply must be examined rather than disregarded merely because an invoice exists.

Automatic interest and a written demand serve different purposes

Within the decree’s scope, Article 4 provides for late-payment interest to run from the day after the due date without a formal notice of default. Article 3 nevertheless allows the debtor to demonstrate that the delay resulted from an inability to perform attributable to a cause for which the debtor was not responsible. Entitlement to interest does not remove the need to check the underlying claim.

A written demand remains useful for identifying invoices, amounts, due dates and payment arrangements while retaining a record of the communication. If further legal effects are intended, its form, content, recipient and evidence of receipt require specific assessment. A generic reminder and a communication prepared to protect a legal right are not necessarily equivalent.

Distinguishing principal, interest and recovery costs

Articles 2 and 5 provide for statutory late-payment interest calculated daily at the reference rate plus eight percentage points; businesses may agree a different rate within the legal limits. The reference rate depends on the relevant half-year. A calculation spanning different periods must therefore check the rate applicable to each, alongside partial payments and the amounts actually overdue.

In the circumstances covered by Article 3, Article 6 recognises recovery costs and a fixed sum of EUR 40 without a formal notice of default, while preserving the possibility of proving greater loss. This does not mean that every expense unilaterally listed is automatically payable. The various items must be separated and justified, avoiding duplication and calculations lacking a verifiable basis.

A hypothetical example: delivery completed and the balance disputed

In an entirely hypothetical case, imagine Alfa supplies equipment to Beta, which pays a deposit but disputes part of the balance. Before claiming interest on the whole invoice, Alfa should collect the contract, order, delivery record, correspondence about the dispute and evidence of the deposit. These documents may show which sums remain due and which issues need further examination.

An orderly reconstruction also helps assess an agreed solution: payment of the undisputed part, technical clarification or a written plan for the remainder. Any agreement should specify amounts, due dates and the treatment of interest and costs. A bare promise to pay without clear terms may leave the operational problem unresolved.

Prepare the file before choosing a remedy

Before starting debt recovery, it is useful to prepare a schedule of each invoice, due date, payment received and supporting document. Add the debtor’s precise identification, contractual terms, any security and the correspondence. The debtor business’s situation must also be checked: establishing a claim and assessing its practical recoverability are separate matters.

This provides a basis for assessing the appropriate course, from an out-of-court demand to court proceedings, and checking its requirements, timing and costs. Issuing an invoice alone guarantees no outcome. A timely, documented assessment supports an informed choice of remedy and helps prevent repeated reminders from taking the place of an effective strategy.

Sources and references

• Normattiva — Legislative Decree No. 231/2002, text in force on 6 November 2026
• Italian Ministry of Economy — Article 4, payment periods
• Italian Ministry of Economy — Article 5, interest rate
• Italian Ministry of Economy — Article 6, recovery costs

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