When did the AD-1 declaration become semi-annual in Italy?

The AD-1 declaration has been semi-annual since January 1, 2026, under D.Lgs. March 28, 2025, no. 43, which reformed the Italian Excise Code (TUA). The operating rules were set by the DM 10 March 2026.

When was the AD-1 H1 2026 declaration due, and what is the next deadline?

The AD-1 declaration for the first half of 2026 (January-June) was due to the Italian Customs Agency (ADM) by September 30, 2026; that deadline has passed. The next deadline is the H2 2026 declaration (July-December), due by March 31, 2027 (DM 10 March 2026, Art. 8).

What is the deadline for the AD-1 H2 2026 declaration?

The AD-1 declaration for the second half of 2026 (July-December) must be filed by March 31, 2027.

Who must file the semi-annual AD-1 declaration?

All operators of a power plant (officina elettrica) with an ADM license or authorization under Arts. 52-54 of the Italian Excise Code (TUA): self-consumption producers, sellers, consumer-sellers, and the other declarant categories updated by D.Lgs. 43/2025.

What are the monthly down payments introduced by DM 10 March 2026?

They are monthly electricity excise payments due by the end of each month (F24, tax code 2806), calculated on the quantities actually consumed (or billed) in the previous calendar month (Art. 55(3) TUA; DM 10 March 2026, Art. 7). They replace the old system of fixed advance payments based on the prior year's tax.

Italy's Semi-Annual AD-1 Declaration 2026: What Changes from the Annual Regime

Q: How did the AD-1 declaration work before 2026?

Before 2026, the AD-1 declaration was annual: a single document covered the entire calendar year and had to be submitted to ADM by March 31 of the following year. The last annual declaration (year 2025) was filed by March 31, 2026 under the old rules.

Since January 1, 2026, under D.Lgs. March 28, 2025, no. 43 and DM 10 March 2026, the AD-1 declaration is no longer annual but semi-annual. Every power plant operator with a license or authorization from the Italian Customs Agency (ADM) must now file two declarations per year: the first covers January-June (H1) and was due by September 30, the second covers July-December (H2) and is due by March 31 of the following year. At the same time, the old system of fixed advance payments has been replaced by monthly payments due by the end of each month, calculated on quantities actually consumed or billed in the previous month. For a full overview of AD-1 obligations under the new rules, see the complete guide to the AD-1 declaration.

Quick definitions

Semi-annual cadence: The filing frequency for AD-1 declarations from 2026 onwards; H1 covers January-June, H2 covers July-December.
H1 2026: First half of the year; meter readings required as of June 30, 2026; declaration was due by September 30, 2026 (deadline passed).
H2 2026: Second half of the year; data as of December 31, 2026; declaration due by March 31, 2027.
Monthly down payment: Electricity excise payment due by the end of each month, calculated on actual consumption (or billing) for the previous calendar month.
True-up (conguaglio): The balance between the excise actually declared for the half-year and the monthly down payments already made in that period.
Power plant (officina elettrica): An installation subject to an ADM license or authorization that produces, transforms, or distributes electricity liable to excise duty.
D.Lgs. 43/2025: Legislative decree that reformed the electricity excise rules in the Italian Excise Code (TUA), in force since January 1, 2026.
DM 10 March 2026: Implementing ministerial decree (Official Gazette no. 66, March 20, 2026) that sets the operating rules for semi-annual declarations, monthly payments, and the 15% bond.

From annual to semi-annual: what changed

Until 2025, the AD-1 declaration followed the calendar year: a single document summarized all excise-liable electricity consumption for the full year and had to be submitted to ADM by March 31 of the following year. Simple in design, but it left a gap of more than twelve months between the end of the tax period and the final settlement.

D.Lgs. 43/2025 cut that gap in half. Starting in 2026, each year generates two declarations, each with its own deadline:

Half-year	Reference period	Deadline
H1 2026	January 1 - June 30, 2026	September 30, 2026
H2 2026	July 1 - December 31, 2026	March 31, 2027
H1 2027	January 1 - June 30, 2027	September 30, 2027

The filing workload doubles. The H1 2026 deadline (September 30, 2026) has passed; the next one is H2 2026, due by March 31, 2027. Operators without automated reminders or a structured management system risk missing the H1 cutoff every year. In practice, a meter reading on June 30 of each year is essential to close out first-half data cleanly, on top of the usual year-end reading.

The transitional rule: the last annual declaration (year 2025)

The switch to semi-annual filing did not eliminate the obligation for the prior year. The declaration for year 2025 remained subject to the old annual rules: it was due by March 31, 2026 using the pre-reform AD-1 form.

The new semi-annual regime therefore applies starting January 1, 2026: the first semi-annual declaration covered H1 2026 (January-June) and was due September 30, 2026. Operators who filed their 2025 declaration on time are caught up; those who did not remain exposed to the penalties set out in the TUA.

Monthly down payments: how they work in 2026

The reform also overhauled the in-year payment mechanism. The old system required fixed monthly advance payments based on the prior year's tax liability, with a final true-up at the annual declaration. Predictable, but disconnected from actual consumption.

Starting January 1, 2026, the monthly payment is due by the end of each month and is calculated on the quantities actually consumed (or billed) in the previous month:

Self-consumption producers: excise on quantities self-consumed in the previous month.
Sellers: excise on quantities billed to end customers in the previous calendar month, broken down by territory.
Consumer-sellers: the sum of the two criteria above.

The true-up settled in the semi-annual declaration covers only the difference between monthly payments already made and the amount actually due for the half-year. For January 2026, a transitional rule applied: the payment due was equal to the December 2025 installment calculated under the old method.

Who is affected: the declarant categories

The semi-annual AD-1 filing requirement applies to every operator of a power plant holding an ADM license or authorization. D.Lgs. 43/2025 redefined the categories of obligated parties in Arts. 52-54 TUA. The main declarant categories are:

Self-consumption electricity producers (commercial solar PV, cogeneration plants, hydroelectric installations)
Electricity sellers to end customers
Renewable energy communities (CER) that distribute energy to their members
Wholesalers and intermediaries that buy electricity for resale
Operators of local distribution networks

Plants generating electricity from renewable sources with a rated output below 20 kW, where all the energy is self-consumed by the producer, remain exempt from the filing requirement. For a full breakdown of the declarant categories and their associated AD-1 sections, see the page on declarant categories and ADM obligations.

What changes in the AD-1 form itself

The AD-1 form has been updated to fit the semi-annual cadence. The main differences from the old annual form:

The “reference period” field now shows H1 or H2 (no longer the calendar year).
Section P (advance payments) no longer exists: the excise due is calculated in section Q, and the new section S (payments statement) reports the payments already made during the half-year.
Any true-up amount owed is paid by the end of the month in which the declaration is filed (DM 10 March 2026, Art. 9); the filing deadlines are September 30 for H1 and March 31 for H2.
Meter data must reference June 30 (H1) or December 31 (H2).

The semi-annual AD-1 form for electricity was approved by ADM Determination prot. 217477/RU of April 9, 2026, which defines two distinct models (power plants and vendors) on a single XML schema. The first operational compilation instructions arrived with ADM Circular 9/D of May 7, 2026 (prot. 263885). The test environment for electronic filing has been available since June 1, 2026, and the H1 2026 declaration was due by September 30, 2026(deadline passed; the next is H2 2026, due by March 31, 2027). Note: Det. ADM 213396 of April 8, 2026 instead concerns the monthly communications for vendors, a separate obligation from the semi-annual declaration.

Legislative sources

D.Lgs. March 28, 2025, no. 43 - TUA reform (semi-annual cadence, Art. 55 TUA)
DM 10 March 2026 - Official Gazette, General Series no. 66, March 20, 2026 (prot. 26A01335) - Arts. 7, 8, 9 (monthly payments, semi-annual declaration, true-up)
ADM Determination prot. 217477/RU of April 9, 2026 - semi-annual electricity (EE) models (power plants and vendors)
ADM Circular 9/D of May 7, 2026 (prot. 263885) - first operational instructions for the semi-annual declaration
ADM Circular 34/2025 (December 2025) - filing instructions for the 2025 AD-1 declaration and preview of the 2026 regime