Changes to the power of attorney for the tax mailbox and similar tax services as from 8 December 2025

As is well known, various services and filings vis-à-vis the tax authorities may be delegated to third parties, in particular to tax advisors, labour law consultants or tax assistance centres. They may be instructed to access the tax mailbox (cassetto fiscale) in order to correct error notices, to download electronic invoices, to manage the advance tax agreement (concordato preventivo) and much more. Until now, various authorisation forms existed for such mandates, which as a rule had to be completed in paper form and submitted to the office. This now comes to an end.

As from 8 December 2025 there is a single authorisation form by means of which the various mandates can be granted digitally. Powers of attorney already granted remain in force until their natural expiry, but at the latest until 28 February 2027. However, caution is required: upon granting a new single power of attorney (delega unica), the previous powers of attorney for the online services of the respective authorised representative covered by the delega unica are entirely replaced; all desired services must therefore be expressly ticked in the new power of attorney.

It must also be borne in mind that, for the single power of attorney, only two authorised representatives may now be appointed in total (previously, different authorised representatives were possible for each service). Here too, more than 2 authorised representatives may remain in place until the natural expiry of the existing powers of attorney.

The changes are based, among other things, on Art. 21 of Legislative Decree No. 1/2024 and subsequently on several implementing measures of the Italian Revenue Agency, most recently that of 7 August 2025. A single power of attorney may be used to delegate powers for the following services:

1. access to the tax mailbox „cassetto fiscale“,
2. services in the field of electronic invoicing (so-called „Fatture & Corrispettivi“): specifically, these are

2.1 the inspection and/or retrieval of electronic invoices or their electronic duplicates;

2.2 the inspection of the data relevant for value added tax purposes;

2.3 the registration of the electronic address (as a rule, the PEC address);

2.4 electronic invoicing and the archiving of electronic invoices, and

2.5 the accreditation and registration of devices (as a rule, cash registers).

1. access to ISA and CPB data (tax reliability index and advance tax agreement),
2. tax collection services (tax liabilities, instalment plans, etc.).

As mentioned above, the taxpayer may appoint a maximum of two authorised representatives for all of the services set out above, which constitutes a considerable restriction compared with the previous rules; a separate notification is sent to the Agenzia for each of these intermediaries.

Please note: the services set out under 2.4 and 2.5 may also be delegated to so-called non-intermediaries; specifically, these powers of attorney are not limited to tax advisors, labour consultants and CAF centres.

The notification of the power of attorney to the Agenzia, and thus its activation, now takes place exclusively by digital means, either by the taxpayer himself or through the authorised representative, for example through a tax advisor.

In the first case, the mandate is granted by logging in with SPID, CIE, CNS or via Fisconline or Entratel to the reserved area, where the grantor selects the path „Il tuo profilo - Deleghe - Intermediari“. Under „Nuova delega“ („New power of attorney“) he enters the tax code of the intermediary to whom he wishes to grant the power of attorney and ticks the boxes of the services to be delegated.

Where, on the other hand, the authorisation is to be granted through third parties (as a rule, tax advisors), the following procedure applies:

1. creation of an electronic delegation in XML format,
2. digital signature by the taxpayer (digital signature or FEA/CIE),
3. digital countersignature by the intermediary,
4. transmission of the delegation via Entratel or the user portal,
5. receipt and archiving of the confirmation.

Transmission may take place either by means of an XML file generated by the tax advisor or CAF centre (signed by the taxpayer and by the intermediary) or via a web service for the creation of an electronic delegation document, which the taxpayer signs with FEA (including FEA/CIE). This should provide a workable solution in particular for non-resident persons, such as legal representatives of companies resident abroad.

The new single powers of attorney remain legally valid until 31 December of the fourth year following the year in which they are granted.

It should be noted that any amendment of a power of attorney entirely replaces the previous one. In particular, attention must be paid to the following circumstance: if, for example, you have hitherto granted a tax advisor, by means of 3 separate powers of attorney, access to the tax account, access to the electronic invoices and access to the advance tax agreement, and you now make an amendment to or confirmation of the power of attorney for electronic invoices, all the other powers of attorney will also lapse and must, where appropriate, be granted or confirmed anew using the single form. Powers of attorney granted to other intermediaries (e.g. to the labour consultant), by contrast, remain unaffected by such an amendment.

The Italian Revenue Agency has published a dedicated guide on the new powers of attorney, which we enclose with this circular as Annex A).

Annex: Guide of the Italian Revenue Agency