Analytical overview of the likely 2026 changes affecting Portuguese companies: reforms to IRC (corporate income tax) and accounting rules are expected to reshape tax liabilities, incentives and compliance obligations. Key areas to watch are adjustments to IRC rates and base-broadening measures, revisions to the SIFIDE R&D credit regime, changes to Zona Franca/free‑zone incentives, and tighter anti‑avoidance and transfer‑pricing rules. Parallel accounting and reporting shifts — including greater digital filing, enhanced transparency requirements and closer alignment with international standards — will raise compliance costs, alter timing of tax recognition and create cash‑flow implications. The net impact will vary by firm size and structure: SMEs may face disproportionate administrative burdens while multinationals must rework cross‑border planning. Practical priorities for businesses are to update accounting systems, revalidate eligibility for incentives (notably SIFIDE and Zona Franca regimes), review transfer‑pricing and tax provisioning, and engage advisers early to manage transitional rules and optimise outcomes.