Reference rate calculator: work out the rent adjustment.
How much a rent changes when the mortgage reference interest rate rises or falls. With the current rate and the rate at the last adjustment.
Calculate the rent adjustment
The net rent falls from CHF 1’850.00 to CHF 1’745.29 per month, CHF 104.71 (5,66 %) less.
Calculation
Official form for rent increases
A rent increase must be notified, with reasons, on the form approved by the canton (Art. 269d of the Swiss Code of Obligations). A letter of your own is not sufficient, and the result of this calculator does not replace the form.
The form is provided by the canton where the property is located, usually through the conciliation authority for tenancy matters. The forms are in the official language of the canton. Examples:
How to calculate
- 1Have the tenancy agreement or last rent notice to hand
- 2Enter the net rent without ancillary costs
- 3Choose the reference rate of the last adjustment
- 4Optional: enter the old and new Swiss consumer price index (CPI)
- 5Calculate and check the steps
Worked example with fictional details
Example excluding inflation and other adjustment grounds: net rent CHF 2,000, previous reference rate 1.50%, new rate 1.25%. A drop of 0.25 percentage points gives a rounded reduction of 2.91%, or CHF 58.20, producing a calculated net rent of CHF 1,941.80.
Compare against the last effective rent adjustment. This example isolates the interest rate effect; it does not establish an individual entitlement. Check other grounds for adjustment and the required notices separately.
Official source, accessed 8 October 2026: Federal Office for Housing: reference interest rate (German)
Frequently asked questions
Usually in the tenancy agreement or in the last rent adjustment notice.
The Federal Office for Housing (FHO) publishes it quarterly. The calculator shows the current rate with its publication date.
No. Indexed and stepped rents as well as turnover based rents are excluded. The result is given without guarantee and is not a substitute for legal advice.
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When the reference rate changes
Every change in the reference rate brings tenant enquiries. ailean answers them, day and night.
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