Facts
A.B. and C.B. (the tenants, respondents) concluded a lease contract with A. AG (the landlord, appellant) on 6 February 2015 for a 5.5-room apartment with an indexation clause and a minimum duration of 5 years. After the expiration of this indexation period, the parties tacitly renewed the lease without indexation.
The tenants repeatedly requested a reduction in rent due to the decrease in the reference mortgage rate, but the landlord refused based on the indexation clause. The tenants finally brought the matter to court to obtain a rent reduction as of 1 July 2020.
Considerations
The Federal Tribunal ruled that the parties to an indexed lease must, under penalty of forfeiture, request rent adjustments - including those based on changes in the reference mortgage rate - for the term of the indexation period, respecting the notice period. If they do not claim any rent modification for this deadline, they are presumed to…