OT23: plan your prevention investments now to reduce your INAIL rate
How the reduction of the average tariff rate for prevention works, which percentages apply based on company size, and why it pays to build the supporting evidence file well in advance.
Legal basis and what it is
The OT23 form is the tool companies use to ask INAIL for a reduction in their average tariff rate for prevention, provided for under Article 23 of the Rules for the Application of Premium Tariffs, set out in the Inter-Ministerial Decree of 27 February 2019. The reduction rewards companies that carry out health and safety improvement measures beyond those already required by law.
The reduction percentages
The size of the reduction depends on the number of worker-years insured under the relevant territorial insurance position (PAT) over the reference three-year period:
- up to 10 worker-years: 28% reduction
- 11 to 50 worker-years: 18% reduction
- 51 to 200 worker-years: 10% reduction
- over 200 worker-years: 5% reduction
A fixed 8% reduction applies instead during the PAT's first two years of activity, regardless of the number of employees. The prevention reduction is added to any reduction in the average rate for a favourable accident record, provided for under Articles 19 and 20 of the same Rules for the Application of Tariffs.
How to qualify: the role of ISO 45001 certification
The OT23 form sets out the eligible measures, organised into several sections (general, social responsibility, cross-cutting, sector-specific). Each measure is worth a certain number of points; a minimum threshold must be reached to access the reduction. Holding a safety management system certified to ISO 45001 by an accredited body often makes it possible to reach the required minimum score directly through a single measure, instead of having to document each improvement separately.
Deadlines to meet
The application must be submitted exclusively online, through the "Reduction for prevention" service on the INAIL portal, by 28 February (29 in leap years). It covers measures carried out in the previous year and, if approved, the reduction applies to the adjustment premium for the year the application is submitted, as part of the annual self-assessment. The form is updated by INAIL every year: the version to use is always the one published for the current year, available on the institutional portal.
Why it pays to build the file in advance
Improvement measures must be documented with precise evidence (invoices, minutes, certificates, management-system records) dating back to the year the application refers to: putting this documentation together right before the February deadline, working back through a whole year of activity, creates a real risk of errors and omissions that can lead to the application being rejected or to a smaller reduction than the company could otherwise have obtained.
Official sources
- INAIL — Reduction of the average tariff rate for prevention (OT23 form) (Italian)
- Legislation — Art. 23, Rules for the Application of Premium Tariffs, Ministerial Decree of 27 February 2019 — Normattiva.it (Italian)
The OT23 form and its instructions are updated by INAIL every year: we always check the version in force for the relevant year before building the file. For an assessment of which measures are eligible in your case, contact us.