Applies to leases without their own update clause. The landlord gives 30 days' written notice and may update only one year after the lease began or was last updated. Stamp duty (10% of the increase) is due on the increase and is tax-deductible.

The coefficient comes from inflation excluding housing over the 12 months to August, is announced by INE that month, and is published in Diário da República by 30 October.

The coefficient is not always what applies: in 2023 INE published 1.0543 and Lei 19/2022 held the increase to 2%, compensating landlords through income tax instead. And in 2021 the coefficient was 0.9997. Rent could go down.