Since January 1, 2026, D.Lgs. 43/2025 has replaced Italy's annual electricity excise declaration with a semi-annual one. Power plant operators now file two AD-1 declarations per year, each followed by a settlement payment (conguaglio). For the first semester of 2026 (H1, January-June) the deadline is September 30, 2026; for the second semester (H2, July-December) the deadline is March 31, 2027. Throughout the semester, each operator remits monthly down payments by the end of the month following the reference month, calculated on the actual excise duty accrued on the previous month's consumption or supplies. These operational rules come from Art. 7 and Art. 8 of DM 10 March 2026, the implementing decree that turns the reform into concrete obligations. New plants also have to file a plant declaration (denuncia di officina) with the Italian Customs Agency (ADM) within 30 days of starting production.
Quick definitions
- Semi-annual deadline
- Filing deadline for the AD-1 declaration: September 30 for H1, March 31 of the following year for H2.
- H1 (first semester)
- Period January-June; the AD-1 declaration covers consumption or supplies for this interval.
- H2 (second semester)
- Period July-December; the AD-1 declaration covers consumption or supplies for this interval.
- Monthly down payment (acconto mensile)
- Payment due by the end of the following month, calculated on the excise duty actually accrued on the previous month's consumption or supplies.
- Settlement (conguaglio)
- Difference between the actual tax declared in the semi-annual return and the sum of down payments made during the semester; due by the same deadline as the declaration.
- Ravvedimento operoso
- Voluntary self-correction of omissions or errors at reduced penalties, available before ADM opens a formal assessment (Art. 13 D.Lgs. 472/1997).
- Plant declaration (denuncia di officina)
- Mandatory notice to ADM within 30 days of starting production; it forms the basis for calculating the surety bond and monthly down payments.
- D.Lgs. 43/2025
- Legislative decree that created the semi-annual structure for AD-1 declarations, in force since January 1, 2026.
Full calendar of AD-1 deadlines for 2026
The complete guide to the AD-1 declaration walks through the quadri and the filing process. This article focuses on dates. Here is the at-a-glance view for the full year 2026:
| Deadline | Obligation | Legal reference |
|---|---|---|
| 28 February 2026 | Monthly down payment for January 2026 | Art. 7 DM 10/03/2026 |
| 31 March 2026 | Monthly down payment for February 2026 | Art. 7 DM 10/03/2026 |
| 30 April 2026 | Monthly down payment for March 2026 | Art. 7 DM 10/03/2026 |
| 31 May 2026 | Monthly down payment for April 2026 | Art. 7 DM 10/03/2026 |
| 30 June 2026 | Monthly down payment for May 2026 | Art. 7 DM 10/03/2026 |
| 31 July 2026 | Monthly down payment for June 2026 | Art. 7 DM 10/03/2026 |
| 31 August 2026 | Monthly down payment for July 2026 | Art. 7 DM 10/03/2026 |
| 30 September 2026 | Monthly down payment for August 2026 | Art. 7 DM 10/03/2026 |
| 30 September 2026 | AD-1 H1 declaration (January-June) + settlement | Art. 8-9 DM 10/03/2026 |
| 31 October 2026 | Monthly down payment for September 2026 | Art. 7 DM 10/03/2026 |
| 30 November 2026 | Monthly down payment for October 2026 | Art. 7 DM 10/03/2026 |
| 31 December 2026 | Monthly down payment for November 2026 | Art. 7 DM 10/03/2026 |
| 31 January 2027 | Monthly down payment for December 2026 | Art. 7 DM 10/03/2026 |
| 31 March 2027 | AD-1 H2 declaration (July-December 2026) + settlement | Art. 8-9 DM 10/03/2026 |
H1 declaration: deadline September 30, 2026
The first semester of 2026 covers January through June inclusive. You must file the AD-1 H1 declaration by September 30, 2026, electronically only, through ADM's Servizio Telematico Doganale (STD). The settlement falls due at the same time: the difference between the actual tax declared and the monthly down payments already paid between February and July 2026. If down payments exceed the actual tax, the credit can offset the H2 declaration or be claimed as a refund.
To meet the September 30 deadline, you need a meter reading at June 30, 2026. Operators with multiple plants or mixed-use consumption must aggregate data by end-use category before opening the telematic form.
H2 declaration: deadline March 31, 2027
The second semester of 2026 covers July through December inclusive. You must file the AD-1 H2 declaration by March 31, 2027. The related settlement falls due on the same date. A meter reading at December 31, 2026 is the starting document for preparing this declaration.
Monthly down payments: logic and amounts
Art. 7 of DM 10 March 2026 created monthly down payments based on actual data from the previous month, replacing the previous fixed instalments calculated on the prior year. The deadline is the end of the month following the reference month: the down payment for January's consumption is due by February 28, for February by March 31, and so on throughout the year.
The calculation base depends on the declarant category:
- Sellers (venditori): excise duty on the quantities billed to end consumers in the previous month, broken down by territorial area (ambito territoriale).
- Own-use consumers (consumatori per uso proprio): excise duty on the quantities actually consumed for own use in the previous month.
- Hybrid operators (consumatori-venditori): the sum of both criteria above.
Keeping a monthly log of meter readings, or of invoiced quantities for sellers, is the minimum needed to calculate each down payment correctly and avoid shortfalls.
Settlement (conguaglio)
The conguaglio closes the account between down payments made during the semester and the actual tax from the declaration. The formula is:
Conguaglio = actual declared tax − sum of monthly down payments made during the semester
If the result is positive, the operator pays the difference by the same deadline as the declaration (September 30 for H1, March 31 for H2). If negative, meaning down payments exceeded the actual tax, the resulting credit can carry forward to the next semester or be claimed as a refund.
New plants: declaration within 30 days of commissioning
Any operator commissioning a new power plant in 2026 must file the plant declaration (denuncia di officina) with ADM within 30 days of starting production, regardless of when the next semi-annual deadline falls. The data in the declaration form the basis for calculating the surety bond (15% of estimated annual excise duty, Art. 10 DM 10 March 2026) and for setting monthly down payments. An error in the declaration ripples through the entire downstream filing cycle.
Penalties and voluntary correction (ravvedimento operoso)
Missing deadlines triggers the penalties under Art. 13 of Legislative Decree 472/1997. Before ADM opens a formal assessment, the ravvedimento operoso procedure is available: a voluntary correction of the omission or error, with penalties reduced on a sliding scale based on how much time has passed since the original deadline. The earlier you correct, the lower the penalty.
Deadlines for Renewable Energy Communities (CER)
Renewable Energy Communities (CER) that qualify as power plants under Arts. 52-54 TUA face the same deadlines as all other operators. The semi-annual structure created by D.Lgs. 43/2025 applies without category exceptions: H1 by September 30, 2026, H2 by March 31, 2027, and monthly down payments by the end of the following month.
Next deadline
September 30, 2026 - first semi-annual AD-1 declaration (H1 2026)
Deklara handles monthly down payments, settlement calculation, AD-1 form filing, and deadline tracking, all built around D.Lgs. 43/2025 and DM 10 March 2026.
Join the waitlist →Frequently asked questions
What is the deadline for the first semi-annual AD-1 declaration in 2026?
The first semi-annual AD-1 declaration for 2026 covers H1 (January-June) and must be filed by September 30, 2026, electronically only, through the ADM telematic portal, under Art. 8 of DM 10 March 2026.
When must the AD-1 declaration for the second half of 2026 be filed?
The H2 declaration (July-December 2026) must be filed by March 31, 2027. This is the second of two annual deadlines set by D.Lgs. 43/2025, which replaced the former annual declaration.
What are the monthly down payments and when are they due?
Monthly down payments are due by the end of the following month, calculated on the actual excise duty from the previous month. For example, the down payment for January 2026 is due by February 28, 2026.
What happens if you miss the September 30, 2026 deadline?
Missed deadlines trigger penalties under Art. 13 of D.Lgs. 472/1997. Before ADM opens a formal assessment, the ravvedimento operoso procedure lets you voluntarily correct the error at reduced penalties.
Do the 2026 AD-1 deadlines apply to Renewable Energy Communities?
Yes. CER that qualify as power plants under the TUA follow the same deadlines: H1 by September 30, 2026, H2 by March 31, 2027, and monthly down payments by the end of the following month.
How is the settlement (conguaglio) calculated at the semi-annual deadline?
The conguaglio is the difference between the actual tax declared and the sum of monthly down payments made during the semester. If down payments exceed the actual tax, the resulting credit can carry forward or be refunded; if they fall short, the difference is due by the same deadline as the declaration.
Further reading
- Complete guide to the AD-1 declaration in Italy - end-to-end overview of quadri, deadlines, and excise calculation after the reform.
- D.Lgs. 43/2025: what changes for AD-1 declarations in 2026 - the reform that brought semi-annual filing and the actual-quantity down payment model.
- DM 10 March 2026: Italy's electricity excise implementing decree - the decree that sets the operational rules for down payments, settlement, and deadlines.
- Power plant surety bond Italy 2026: the new 15% calculation - the bond adjustment follows the same semi-annual deadlines.