The energy efficiency deduction

The deduction is founded on the relevant article of the 2013 decree law governing energy upgrading works, with rates for each tax year set by the budget laws. The two sources are read together in each tax year.

For the 2026 tax year the rate is 50 per cent for the claimant's main home and 36 per cent for other properties. Neither rate depends on the type of work.

One access requirement distinguishes the ecobonus from the other deductions: it applies to existing buildings of any land registry category, on condition that they already have a heating system. Checking that condition precedes any assessment of eligibility.

The scope covers operations producing a measurable energy improvement and meeting the applicable technical requirements. The technical requirements are the condition and not an accessory.

It typically covers reducing the energy demand for heating, improving the thermal insulation of horizontal and vertical opaque elements, replacing windows and doors, installing solar shading, installing solar panels for hot water production, and replacing winter heating systems within the limits considered below. Each category carries a cap of its own.

One recurring clarification: photovoltaic panels, which produce electricity, do not fall within the ecobonus and follow their own regime. Confusion with solar thermal panels is frequent and produces incorrect estimates.

The caps are not single but differentiated by type of work, under the technical requirements laid down by the 2020 ministerial decree connected with the regime. The applicable cap follows from the actual type of work.

Type of work	Limit
Replacement of windows and doors, solar shading, solar panels for hot water	up to 60,000 euros
Works on horizontal and vertical opaque elements	up to 60,000 euros
Replacement of winter heating systems and water heaters	up to 30,000 euros

One technical qualification accompanies this table and should be known because most general sources omit it. The caps combine with maximum unit costs per unit of area.

The historic ecobonus caps are in several cases expressed as a maximum deduction rather than as a simple limit on the amount that may be invoiced. They must therefore be read together with the year's rate and with any unit cost caps applying to individual items. The effective limit depends on the combination of works, the characteristics of the building and the specific eligible costs.

The operational consequence is that a table of caps is not enough to size the benefit: the calculation must be carried out on the actual case, using the current technical guidance notes of the designated body. The guidance notes are updated periodically and should be consulted in their latest version.

On one point the rule is clear and useful: where several different types of work are carried out, their respective caps are added together, within the limit applying to each item. The addition operates across distinct categories and not on the same operation.

This is the limitation that most changes the design of building services, and it should be applied precisely. It concerns boilers fuelled by fossil fuels.

Since 1 January 2025 works replacing winter heating systems with single boilers fuelled by fossil fuels are no longer eligible, including condensing boilers and condensing warm air generators. The exclusion also covers condensing technologies.

Lower impact solutions remain eligible: heat pumps, hybrid systems, biomass generators and micro cogeneration units, including where the latter run on fossil fuels. The technical conditions of each solution must be checked separately.

One transitional provision should be known: expenditure incurred up to 31 December 2024 on works now excluded remains eligible, even where the works were completed later. The relevant date is when the expenditure was incurred.

The exclusion should not be confused with certified hybrid systems or with heat pumps, which remain fully eligible on the conditions provided. Certification of the hybrid system is the condition of eligibility.

The ecobonus is the deduction with the greatest technical content, and the requirements do not coincide with the energy class stated by the manufacturer alone. The class stated by the manufacturer does not replace checking the parameters.

Depending on the work it is necessary to verify thermal transmittance values, the efficiency of the systems, the performance of heat pumps, solar transmission factors, emission characteristics and unit cost caps. Each parameter carries its own threshold set by the technical decree.

The documentation required may include the technical certification, product data sheets, supplier declarations and the energy performance certificate. The exact list varies with the type of work.

The guidance notes published by the designated body are the operational reference for checking values, documents and caps applicable to the actual case, and consulting them in their current version is part of the technical work. A superseded version produces checks made against values no longer applicable.

Works eligible for the ecobonus require data to be transmitted electronically to the designated body within ninety days of completion of the works. The period runs from completion of the works and not from handover.

A recent update to the portal introduced specific rules on when the period starts for works spanning its entry into operation, and the applicable deadline must be checked against the start and completion dates of the project. The check is made against both dates and not one alone.

The subject is examined in the page devoted to the notification, and it is among the deadline bound formalities most frequently omitted. It is worth placing on the site closing checklist.

The deduction for ecobonus work cannot be combined with other tax reliefs provided for the same works by other statutory provisions. The prohibition operates on the same operation.

It is however possible to use different reliefs for different operations, within their respective caps. Separating the operations in the accounts is the condition.

The practical consequence concerns the structure of the bill of quantities. On mixed works, separating in the accounts the operations attracting different deductions is the condition for combining them, and must be set up when the bill is prepared rather than reconstructed afterwards.

Confusing solar thermal and photovoltaic panels is the first, and attributes to the ecobonus work that follows a different regime. Photovoltaics follow a regime of their own.

Reading the caps as simple spending limits is the second, and produces a sizing of the benefit that the calculation on the actual case contradicts. The calculation must be carried out with the maximum unit costs.

Designing a boiler replacement without checking the exclusion is the third, and makes ineligible works the client was relying on. The check belongs before the financial plan is set.

Assuming the building is eligible without checking that a heating system exists is the fourth. The existence of a heating system is a condition of access.

Combining different reliefs on the same operation is the fifth, and breaches the prohibition on combination. Combination is permitted only across distinct operations.