The IRS – Personal Income Tax remains, in 2026, one of the most important tax obligations for taxpayers in Portugal. Knowing the deadlines and completing each phase on time is essential to avoid fines, maintain deductions, and secure a higher refund.
In 2026, several deadlines were harmonized and concentrated at the beginning of March, making the tax calendar simpler but also more demanding.
At FA ACCOUNTING, our experience shows that most issues do not arise during the submission of the tax return itself, but earlier, when mandatory steps are overlooked. This guide summarizes the official deadlines and explains what needs to be done at each phase.
Why is it important to follow the IRS calendar?
The IRS process does not “begin” in April. It involves several earlier procedures that directly influence the tax due or the refund amount—such as invoice validation and updates to the household structure.
IRS Calendar 2026: Key Deadlines
Until February 16, 2026 — Rental Contract Communications
- Report the duration or termination of rental contracts in effect during 2025.
- Mandatory for tenants (to deduct rent) and landlords (to declare rental income).
March 2, 2026 — The Key Deadline
Since the last day of February falls on a weekend, several obligations move to the next business day: March 2, 2026.