Agenzia delle Entrate issues ISA 2026 and tax agreement rules

The Italian Revenue Agency (Agenzia delle Entrate) has issued Circular No. 4/E, outlining operational rules for the biennial preventive agreement (concordato preventivo biennale) for the 2026-2027 period.

The guidelines establish a direct link between data declared in the ISA 2026 models and the tax authority's proposed taxable base for business and self-employed income. The document includes a comprehensive update to all 173 ISA models for the 2025 tax period, featuring a deep revision of 85 sector indicators to better reflect current macroeconomic and market dynamics.

Key provisions include the simplification of required information and strict prohibitions against artificial accounting adjustments intended to manipulate ISA scores for the purpose of the biennial agreement. The circular also clarifies procedures for the submission, rectification, and revocation of agreements.