AD-1 Declaration Deadlines 2026 in Italy: Semi-Annual Calendar, Down Payments and Settlement

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 expired on September 30, 2026; the next one is the second semester (H2, July-December), due by March 31, 2027. Throughout the semester, each operator remits monthly down payments by the end of each month, calculated on the actual excise duty 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) in advance of starting the activity (Art. 53-bis(1) TUA).

October 2026 update: the H1 2026 deadline of September 30, 2026 has passed, and the next filing is H2 2026 by March 31, 2027. The first operational compilation instructions came with the ADM Circular 9/D of May 7, 2026 (prot. 263885), which approves the two distinct models for power plants and vendors (Det. 217477/RU) and sets the test environment opening on June 1, 2026.

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 each month, calculated on the excise duty 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; paid by the end of the month in which the declaration is filed (Art. 9 DM 10 March 2026).

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, filed in advance of starting the activity (Art. 53-bis(1) TUA); it forms the basis for calculating the surety bond and monthly down payments. A separate thirty-day term under Art. 53-bis TUA applies to changes at a plant that already exists, corporate changes and cessation.

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, kept as a reference. As of October 15, 2026, every row up to and including September 30, 2026 is already behind us, and the next declaration deadline is March 31, 2027 (H2):

H1 declaration: deadline expired on September 30, 2026

The first semester of 2026 covers January through June inclusive. The AD-1 H1 declaration had to be filed by September 30, 2026, electronically only, through ADM's Servizio Telematico Doganale (STD), and that deadline has passed. If you have not filed yet, do not wait for the H2 cycle: file the H1 declaration as soon as possible and read the section on voluntary correction (ravvedimento operoso) below. The settlement for H1 is the difference between the actual tax declared and the monthly down payments already paid for the semester, and it is paid by the end of the month in which the declaration is filed (Art. 9 DM 10 March 2026). If down payments exceeded the actual tax, the credit can offset the H2 declaration or be claimed as a refund.

The meter reading at June 30, 2026 is the starting document for any H1 filing still outstanding. Operators with multiple plants or mixed-use consumption must aggregate data by end-use category before opening the telematic form.

H2 declaration: next 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. This is the next declaration deadline. The related settlement is paid by the end of the month in which the declaration is filed, so by March 31, 2027 if you file on the deadline day. 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. Each down payment is due by the end of the monthand is calculated on the previous calendar month's quantities (Art. 55(3) TUA; Art. 7 DM 10 March 2026): the payment due by February 28 rests on January's consumption, the one due by March 31 on February's, and so on throughout the year. Payment goes through F24 with tax code 2806. The January 2026 instalment was the exception: it followed the old method, at the December 2025 rate.

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 end of the month in which the declaration is filed (Art. 55(4) TUA; Art. 9 DM 10 March 2026). 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 in advance of commissioning

Any operator commissioning a new power plant in 2026 must file the plant declaration (denuncia di officina) with ADM in advance of starting the activity, regardless of when the next semi-annual deadline falls. Art. 53-bis TUA sets two different timings, and they are easy to confuse: the notice for a new activity is an advance one (Art. 53-bis(1) TUA), while the thirty-day term covers changes at a plant that is already a power plant, corporate changes and cessation. The data in the declaration form the basis for calculating the surety bond (15% of estimated annual excise duty, Art. 53-bis(1) TUA and Art. 5 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)

A late or omitted declaration is sanctioned under the TUA (Art. 59(1)(c): 2 to 10 times the evaded tax, minimum EUR 258 per declaration; Art. 50(1): EUR 500 to 3,000 as the general rule). Before ADM opens a formal assessment, the ravvedimento operoso procedure (Art. 13 of Legislative Decree 472/1997) is available, though not for a declaration filed more than 90 days late (Art. 13(2-ter)): 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, which matters now that the H1 2026 deadline has passed.

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 liable parties: H1 was due by September 30, 2026, H2 is due by March 31, 2027, and monthly down payments fall due by the end of each month. The semi-annual structure reaches only the soggetti obbligati, though. Parties that fall outside that perimeter under Art. 56-bis TUA (total grid injection, transport and distribution) stay on an annual filing (a declaration or, for producers in total grid injection, an annual communication), next due by the end of March 2027, as ADM Circular 9/D of May 7, 2026 confirms. The ADM model for these filings had not been published as of October 15, 2026.

Frequently asked questions

Has the H1 2026 AD-1 deadline passed, and what is the next one?

Yes. The H1 2026 declaration (January-June) was due by September 30, 2026, and that deadline has expired. The next one is the H2 2026 declaration (July-December), due by March 31, 2027. Filing is electronic only, through the ADM telematic portal, under Art. 8 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 next deadline and the second of two set each year 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 paid by the end of each month, calculated on the excise duty on the quantities billed or consumed for own use in the previous calendar month (Art. 55(3) TUA; Art. 7 DM 10 March 2026). For example, the payment due by February 28, 2026 is based on January 2026 quantities.

What if I missed the September 30, 2026 deadline for H1?

The deadline has passed, and a late or omitted declaration is sanctioned under the TUA (Art. 59(1)(c): 2 to 10 times the evaded tax, minimum EUR 258 per declaration; Art. 50(1): EUR 500 to 3,000 as the general rule). Before ADM opens a formal assessment, the ravvedimento operoso procedure (Art. 13 of Legislative Decree 472/1997) lets you voluntarily correct the error at reduced penalties, but not for a declaration filed more than 90 days late (Art. 13(2-ter)).

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 was due by September 30, 2026, H2 is due by March 31, 2027, and monthly down payments fall due by the end of each 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 paid by the end of the month in which the declaration is filed.

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 is adjusted quarterly, not on the semi-annual deadlines.
• ADM Circular 9/D 2026: first instructions for the semiannual electricity declaration - the distinct models for power plants and vendors, the test environment, and monthly rounding for the H1 2026 filing.