The basis and the scope
The deduction is founded on the relevant article of the 2013 decree law on seismic works, with rates set for each tax year by the budget laws. The two sources are read together in each tax year.
The territorial scope is delimited: the relief applies to buildings in seismic zones 1, 2 and 3 under the official classification. Zone 4 is excluded, and checking the zone precedes any assessment.
No particular use is required. Both residential and non residential properties qualify, including industrial buildings, plants and offices. The building must be existing and properly registered, with its planning position in order.
The end of the rates tied to risk class improvement
This is the decisive point of this page, and it must be stated without ambiguity because many sources in circulation still report the earlier regime. It concerns the removal of the link between the rate and class improvement.
Until 2024 the rate depended on the improvement in risk class achieved, with percentages rising to 70 and 80 per cent for a one or two class improvement, to 75 and 85 per cent for works on the common parts of buildings, and to 110 per cent under the Super sismabonus regime. None of those percentages applies today.
Since 2025 that mechanism no longer operates. The rate is single and does not depend on the number of classes gained.
The rates in force apply to all categories of eligible works, including those that until 2024 attracted a higher deduction: works achieving an improvement of one or two risk classes, works on the common parts of buildings, and works carried out by demolition and reconstruction of whole buildings by construction firms with subsequent sale. The uniformity of the rates is the defining feature of the current regime.
Anyone consulting a guide still showing percentages between 70 and 85 per cent is reading an outdated source. It is the check to make before passing a figure to a client.
The rate and the cap
For the 2026 tax year the rate is 50 per cent for works on the unit used as the claimant's main home and 36 per cent for works on any other property. Both rates follow from use and not from the technical result.
The spending cap is 96,000 euros per property unit. The number of units is counted at the start of the works.
The deduction is spread over ten equal annual instalments, under the arrangement introduced by the 2024 decree and maintained since. Each instalment can be used only in the year to which it relates.
One practical effect deserves stating. Because the rate no longer rewards a class improvement, the tax incentive no longer distinguishes between a modest improvement and a full seismic upgrade. The choice of intervention level therefore returns to resting on independent technical and financial considerations rather than on marginal tax yield.
| Element | Until 2024 | 2026 regime |
|---|---|---|
| Rate, one class improvement | 70 per cent | 50 or 36 per cent by use |
| Rate, two class improvement | 80 per cent | 50 or 36 per cent by use |
| Rate, common parts | 75 or 85 per cent | 50 or 36 per cent by use |
| Duty to certify the class | Required | Required |
| Reasonableness attestation | Required | Required |
Certification of the risk class
The certification requirement remains fully in force, and its survival deserves emphasis precisely because the rate no longer depends on the result achieved. The risk class must still be attested before and after the works.
The effectiveness of the works in reducing seismic risk is certified by the professionals responsible for the structural design, for supervising the structural works and for the structural inspection, within their respective competences and under the 2017 ministerial decree governing the matter. Each of the three roles attests within its own competence.
The certification attests the building's risk class before and after the works, determined under the ministerial guidelines that set out the classification on a multi level scale. The determination follows the method the guidelines define.
The professionals involved also attest that the expenditure incurred is reasonable in relation to the eligible works. The reasonableness attestation must be built on documented references.
That last element deserves attention. The reasonableness attestation is an economic judgment the professional gives with direct tax effects, and its soundness is open to verification on audit. Building the bill of quantities from items traceable to documented price references is not a precaution but the condition on which the attestation can stand.
The purchase variant
A particular situation concerns buyers of a property in a building demolished and rebuilt to seismic standards. The benefit follows the buyer and not the firm.
The benefit belongs to the buyer where the works are carried out by construction or property refurbishment firms which, within the period the rules set from completion, sell the property on. The period for the sale should be checked against the text in force.
Here too the rates are the ordinary ones: the enhanced version of this variant no longer applies to expenditure in the current tax year. Estimates prepared under the enhanced regime cannot be carried over.
The formalities that distinguish it
The sismabonus differs from the ecobonus on one formality that causes recurring confusion. It concerns the electronic notification to the designated body.
Electronic notification to the body responsible for energy matters is not required as a rule for seismic works, unlike for the ecobonus. Some sources indicate it for particular situations, and the position should be checked against the actual works and current practice.
What remains fully required is payment by compliant traceable means, retention of invoices, the building consents and the certification with its accompanying reasonableness attestation. The set should be built during the works rather than at the end.
On mixed works covering both seismic strengthening and energy upgrading, the formalities of the two regimes add up and separating the operations in the accounts becomes the condition for claiming both deductions. The separation should be set up while the bill of quantities is drawn up.
The most frequent errors
Applying the rates tied to risk class improvement is the first, and is today the most widespread error in this field because many sources still report them. The check should be made against the year's budget law.
Assuming the relief applies in seismic zone 4 is the second, and that zone is excluded. The seismic zone of the property should be checked before any estimate.
Concluding that, because the graduated rate has gone, the risk class certification is no longer needed is the third. The requirement remains.
Giving the reasonableness attestation without building the bill of quantities on documented references is the fourth, and exposes the professional on audit. A bill without references is the most exposed position on audit.
Note: the information in this page relates to Italy and refers to the tax year stated. Many sources in circulation still report the rates tied to risk class improvement, which no longer apply: the text in force and the revenue administration's tax guide should be checked before any operational use.