Written with people moving from Turkey in mind. The Portuguese rules still apply more broadly.
Annual Rent Increases
Landlords cannot raise your rent arbitrarily. The annual increase is capped by a government coefficient based on inflation (published every October for the following year). For 2026, the cap is strictly regulated.
The landlord must notify you in writing (registered letter) at least 30 days before the increase takes effect. If the contract does not explicitly mention annual updates, the rent must remain fixed.