Reference rate, inflation, rising costs — an adjustment is only valid in the prescribed form. From the reason to the new amount due.

1. 1
   Establish the type of lease – standard, index-linked or stepped. What counts as a valid reason follows from it: for an index-linked lease it is the consumer price index alone.
2. 2
   Calculate in the rent adjustment tool: reference rate, inflation and general cost increases together give the new net rent. An increase you choose not to apply can be recorded as a reservation – the rent stays as it is, the claim survives.
3. 3
   Produce the official form, with the municipality's conciliation authority. An increase is valid only with it and within the deadline: at least 10 days before the notice period begins, on a termination date (CO 269d). Since 1.10.2025 stepped rents no longer need the form.
4. 4
   Do not forget reductions. When the reference rate falls, the tenant is entitled to a reduction. The landlord may offset accrued inflation and cost increases against it.
5. 5
   Record the dates – dispatch and effective date in the deadline calendar. From the effective date collection applies the new rent; the old amount stands for the months already past.