Facts
On 21 December 1990, [A.] rented commercial premises to [B. SA] in properties X. and Y. in Fehraltorf. The rental contract began on 16 February 1991 and could be terminated for the first time on 31 March 1996, with seven months' notice. The contract provided for a five-year extension option, which had to be exercised before 31 March 1995. The annual rent was set at 589'740.-- Swiss francs, but was reduced to 383'220.-- Swiss francs for the duration of the contract, i.e. until 31 March 1996. The rent could be adjusted according to changes in the consumer price index.
On 1 January 1995, the rent was 442'494.-- Swiss francs per year, after several adjustments based on the consumer price index. [B. SA] did not exercise its extension option, but the parties continued the rental contract without a termination date. [A.] then increased the rent to 693'152.-- Swiss francs per year, which [B. SA] contested before the rental conciliation commission.
Considerations
The Federal Court examined the question of whether the combination of an indexation clause and a staggered clause in a rental contract is admissible. It considered that, in principle, an agreed rent cannot be unilaterally modified by either party during the contract period. However, Swiss law provides for two adjustment clauses, indexation (Art. 269b CO) and staggering (Art. 269c CO), which allow the rent to be modified during the contract period.
The Federal Court considered that the combination of these two clauses in the same rental contract is not admissible, as it could lead to excessive rent increases. It also considered that, in this case, the staggered clause was clearly provided for in the contract and that the rent increase…