Renewable Energy Communities (CER, Comunità Energetiche Rinnovabili) formed under D.Lgs. 199/2021 are liable parties for electricity excise when they produce, share, or supply energy through the grid. From January 1, 2026, the CER, as a collective legal entity, must file the AD-1 return on a semi-annual basis under Art. 53 TUA (D.Lgs. 43/2025). The first deadline is September 30, 2026for the H1 semester (January to June 2026). The declarant is the CER's legal representative on file with the Italian Customs Agency (ADM), not the individual photovoltaic self-producer or consumer members. Missing the deadline triggers a penalty of 100% to 200% of the tax due, with a €500 minimum. CER managers new to electricity excise should pair this article with our complete guide to the AD-1 declaration for the underlying quadri, deadlines, and rate logic.

Quick definitions

CER (Renewable Energy Community): Standalone legal entity under D.Lgs. 199/2021 that aggregates renewable energy producers and consumers inside a geographic boundary set by GSE rules.
Liable party: The CER itself as a legal entity, not the individual members. Holds the ADM license or authorization under Art. 53 TUA.
Collective self-consumption: Energy produced by CER plants and shared between members without any supply to third parties. Counts toward the excise calculation under Art. 52 TUA.
BESS: Battery Energy Storage System. Charge and discharge data go into Quadro E of the AD-1.
RIU: Rete Interna d'Utenza: a private internal distribution network inside a delimited perimeter. Requires Quadro H.
Semi-annual cadence: AD-1 filing frequency set by D.Lgs. 43/2025: H1 (Jan to Jun) by September 30, H2 (Jul to Dec) by March 31 of the following year.
20 kW threshold: Nominal capacity below which self-consumed renewable plants are exempt from excise (Art. 52, c.1 TUA).

What is a Renewable Energy Community for excise purposes

A CER is a standalone legal entity (an association, cooperative, third-sector body, or not-for-profit company) that aggregates renewable energy producers and consumers inside a geographic boundary set by GSE rules. For excise purposes, ADM treats the CER as a single operator: the CER itself, not its members, holds the ADM license or authorization and files the AD-1 declaration. Each member stays responsible for their own final consumption, but the entity as a whole owns the declaration of energy produced and shared.

Who is the liable party in a CER

The liable party is the CER itself as a legal entity, under Art. 53, c.1 or c.3 TUA depending on the setup:

Art. 53, c.1 TUA (operating license), if the CER supplies energy to third parties or to the grid outside collective self-consumption
Art. 53, c.3 TUA (notification), if the CER produces renewable energy with capacity between 20 kW and 200 kW and injects into the grid, without a full license
Art. 53, c.5 TUA (own-use authorization), if the energy produced is consumed collectively by the members with no supply to third parties

The declaration is signed by the CER's legal representative. When the CER runs both collective self-consumption and energy supplied to third parties, ADM may classify it as a consumer-seller and require additional quadri (sections).

Which AD-1 quadri a CER must complete

The mandatory quadri (sections) depend on the CER's technical setup:

CER setup	Required AD-1 quadri
Collective self-consumption only	Quadro A, Quadro C
With grid supply to third parties	Quadro A, Quadro B, Quadro C
With BESS (battery storage system)	Quadro A, Quadro B (if supply), Quadro C, Quadro E
With integrated RIU	Quadro A, Quadro B, Quadro C, Quadro H

Quadro A captures identifying data and aggregate volumes. Quadro C covers energy produced from renewable sources. Quadro B applies whenever you supply third parties. Quadro E logs BESS charge and discharge data for the semester. Quadro H is specific to RIUs (internal distribution networks).

2026 semi-annual deadlines

Semester	Reference period	Filing deadline
H1 2026	01/01/2026 to 30/06/2026	30/09/2026
H2 2026	01/07/2026 to 31/12/2026	31/03/2027

Take the first meter reading for the H1 declaration on June 30, 2026. Take the H2 closing reading on December 31, 2026.

CER with BESS or mixed use

CERs with battery storage systems (BESS) need to track energy charged into the battery separately from energy discharged, because the two volumes feed the excise calculation differently. Energy discharged from the BESS and supplied to final consumers is excisable. Energy self-consumed directly by CER members counts as collective self-consumption. Quadro E of the AD-1 captures these flows for the semester.

Mixed use, where part of the energy produced is self-consumed and part is supplied, requires separate accounting by intended use. A CER without separate metering across uses will struggle to complete the required quadri correctly.

CER vs RIU (Internal Distribution Networks)

A CER can aggregate plants and consumption points that are physically far apart, linked through the public distribution grid. An RIU (Rete Interna d'Utenza) is a private network connecting multiple injection and withdrawal points inside a physically bounded perimeter (e.g., an industrial site or a complex).

The distinction matters for ADM: RIUs file Quadro H, CERs without an RIU do not. A CER that also runs an internal RIU (e.g., condominiums with a shared private network) must file both and declare the two perimeters separately.

Checklist for the CER manager

Confirm the CER holds an ADM license or authorization issued to the CER as a legal entity, not to individual members
Identify the technical setup: collective self-consumption only, grid supply, BESS, or RIU
Determine which AD-1 quadri are mandatory for that setup (see the table above)
Set up monthly metering of the kWh shared and supplied at each measurement point, which is required for monthly payments from 2026
Take meter readings on June 30, 2026 to close out the H1 semester data
Calculate and post the surety bond (15% of estimated annual excise, per DM March 10, 2026)
File the H1 AD-1 declaration by September 30, 2026

Legal sources

D.Lgs. 43 of March 14, 2025, Art. 53 TUA (liable parties and declarants)
ADM Circular 32/2025, new intended uses and AD-1 quadri instructions for CERs
DM March 10, 2026, semi-annual return, monthly payments, 15% bond
D.Lgs. 199 of November 8, 2021, setup and rules for CERs in Italy
D.Lgs. 504/1995 (TUA), Arts. 52 to 54, electricity excise legal basis

Deklara handles CER filing obligations end to end: from power plant registration to the semi-annual AD-1 declaration, with support for all 8 declarant categories under the TUA.

Renewable Energy Communities (CER) and the AD-1 Declaration in Italy: Obligations, Declarant Categories and 2026 Deadlines