Fixed or SARON: choose the uncertainty you can live with
Compare payment predictability, rate sensitivity and exit conditions instead of chasing the lowest opening rate.
Every model has a different risk
The mortgage decision is not a contest to predict interest rates perfectly. A fixed-rate agreement offers a known rate for an agreed term but can restrict early exit. A reference-rate arrangement exposes payments to its contractual rate formula and margin. Compare how each fits the time you expect to own the property, your reserve and your ability to absorb changes. A cheaper initial payment is only attractive if you understand which uncertainty you accept in exchange and can fund it.
Read the reference-rate formula
SARON is a reference rate, not your final mortgage price. Request the contract’s compounding method, observation period, margin, floor and billing frequency. Ask when the amount becomes known and what notice applies to a product change. Do not calculate the expected invoice by simply adding today’s displayed SARON to a margin without reading the agreement. The SNB explains monetary-policy transmission, while your lender determines the contractual calculation and conditions governing your actual loan.
Hypothetical stress budget
Take CHF 700,000 of unchanged debt. A hypothetical move from 2% to 3.5% raises annual interest from CHF 14,000 to CHF 24,500, a CHF 10,500 difference before other costs. It is a scenario, not a forecast. Ask whether that extra CHF 875 per month could be paid from income or only by consuming reserves. Comparing the result with a fixed quotation helps price predictability without claiming that either rate path will occur.
The exit question matters equally
Ask both providers what happens after a sale, separation, relocation or refinancing. Obtain a worked early-exit calculation rather than a statement that penalties are “standard”. A fixed agreement can be unsuitable for a near-term move even if the rate looks attractive. A SARON framework agreement may also include terms that limit switching. Treat portability, transfer to a buyer and conversion to another product as questions requiring approval, not universal borrower rights inferred from a brochure.
Do not confuse mixed with diversified
Splitting debt across maturities can reduce dependence on one renewal date, but it can also complicate moving all financing to another lender. Ask whether remaining tranches can be transferred, bought out or aligned later and at what cost. A mixed structure is useful only when its operational consequences are understood. It does not automatically diversify household income or eliminate rate exposure. Draw a maturity calendar and calculate how much debt remains locked on every potential review date.
Choose a policy you can maintain
Write a simple borrowing policy: the maximum payment you can absorb, the minimum reserve, expected ownership horizon and conditions that trigger a review. Then compare offers against that policy on identical debt and amortisation assumptions. Avoid switching merely because headlines predict the next rate cut. A good choice recognises that future rates and life events are uncertain, and selects contractual terms the household can continue to honour across plausible scenarios rather than only the most optimistic one.
Sources and further reading
Original Clearwise analysis. External reporting provides context; rules and contract terms must be verified with the competent authority or provider. Some press articles may require a subscription.
Apply this to your situation
Compare your actual documents and clarify what matters before making a commitment.
Request a free consultationGeneral guidance, not a binding quote or personalised legal, tax or investment advice. Examples are hypothetical and results are not guaranteed.
