IRS 2026 - the filing window opens on 1 April and closes on 30 June
Summary
Modelo 3 returns for 2025 income are filed between 1 April and 30 June 2026, on the Portal das Finanças. Tax still due is paid by 31 August. First IMI instalment by 31 May.
What this means for you
The yearly peak in traffic and in demand for accountants. Every individual filer and freelancer files in this window.