Refund of electricity excise duties and increased interest: Order no. 29757 of 2025

The issue of the refund of electricity excise duties unduly paid by consumers continues to be at the center of the Italian legal debate. Recently, the Court of Cassation has returned to rule on a crucial aspect of this litigation: the rate of interest applicable to the sums to be reimbursed. With Order no. 29757 of November 11, 2025, the judges of legitimacy clarified a fundamental principle that significantly strengthens the protection of end consumers against suppliers.

The context of the dispute and the right to a refund

The case arises from the illegitimacy of provincial surcharges on electricity excise duties, applied in Italy in violation of European Union directives. Consequently, many consumers have initiated actions for the recovery of undue payment pursuant to Art. 2033 of the Italian Civil Code to obtain the restitution of amounts paid as reimbursement to their suppliers. In the case at hand, the dispute involved C., represented by D. Z. P., and V., represented by C. D., focusing precisely on the entitlement to and the measure of the legal interest to be calculated on the sum subject to restitution.

The decision of the Court of Cassation and the scope of increased interest

The Supreme Court, confirming the decision of the Court of Appeal of Turin, established that the consumer's claim is subject to legal interest at the increased rate provided for by Art. 1284, paragraph 4, of the Civil Code. This provision stipulates an interest rate equal to that provided for by special legislation for late payments in commercial transactions, which is usually much higher than the ordinary legal rate, starting from the date the judicial claim is filed.

To the claim brought by the end consumer for the recovery of the provincial surcharge on electricity excise duty, unduly paid to the supplier as reimbursement in contrast with EU law, the legal interest at the rate provided for by Art. 1284, paragraph 4, of the Civil Code is applicable, given that the provision contained therein, by leaving the parties the possibility of determining its measure, serves to exclude its mandatory and non-derogable nature and not to limit its field of application.

This principle clarifies that the increased interest rate is not limited solely to contractual relationships in which the parties have failed to agree on interest, but also extends to restitution obligations arising from an undue payment (Art. 2033 of the Civil Code). The fact that the rule allows parties to agree on a different rate demonstrates that the provision does not have a mandatory, non-derogable character, thus expanding its applicability to protect the creditor who finds themselves having to take legal action to recover their funds.

Practical consequences for consumers and businesses

The ruling of the Court of Cassation outlines a very favorable framework for those who have paid undue taxes, highlighting the following key points:

• Greater economic relief: The application of the rate pursuant to Art. 1284, paragraph 4, of the Civil Code guarantees the consumer compensation for damages due to delay that is significantly more substantial than the ordinary legal rate.
• Deterrent for suppliers: The high interest rate discourages dilatory behavior by energy suppliers in returning the sums unduly received.
• Alignment with EU law: The principle of the effectiveness of consumer protection in the face of tax levies declared incompatible with the European legal order is reaffirmed.

Conclusions

Order no. 29757 of 2025 represents a fundamental piece in the jurisprudence relating to the refund of energy excise duties. By recognizing the applicability of commercial interest rates also to actions for the recovery of undue payment, the Court of Cassation not only ensures full and effective protection for the end consumer but also sends a clear signal of rigor against delays in the fulfillment of restitution obligations.