Kernrechtsfrage
Whether the tenant's claim for repayment of overpaid charges was time-barred.
Extrahierter Entscheid
The claim was not time-barred. For accepted accounts, the one-year period under Art. 67 CO began at the earliest on 8 May 2008, and the conciliation filing on 23 June 2008 was timely.
Extrahierte Begründung
The tenant only had sufficient certainty to sue when the landlord communicated the error concretely. Earlier correspondence showed suspicion, not effective knowledge of the repayment claim and its extent.