When is it worthwhile to switch from SARON to a fixed-rate mortgage?

The 3-point decision matrix

To determine the optimal time to switch from SARON to a fixed-rate mortgage, you must combine three factors: An interest rate difference (spread) of less than 0.5% between SARON and long-term fixed-rate mortgages, emerging inflation signals in the euro area/Switzerland and a dwindling personal risk budget. When long-term swap rates start to rise, logging in a fixed-rate mortgage in good time demonstrably increases your financial planning security and protects you from expensive interest rate peaks.

The market factor: Why the yield curve is everything

There is a basic economic law on the Swiss mortgage market: The expectations of market participants determine the prices of the future. The Swiss National Bank (SNB) sets the pace for SARON with the key interest rate, but fixed-rate mortgages often anticipate this development months in advance via the so-called swap market. Anyone who only switches when interest rates are already rising is usually too late.

Strategic indicators for change

In order to time the switch efficiently, you must not only look at the current SARON interest rate — you must keep an eye on the futures markets.

• Narrowing the spread: If the interest rate for a 5- or 10-year fixed-rate mortgage is only slightly above the current SARON rate, the “insurance premium” for the fixed-rate mortgage is historically low. That is a strong buying signal.
• Inverted yield curve: When long-term fixed-rate mortgages are suddenly cheaper than short-term SARON money market loans, the market signals an economic slowdown. This can be a unique opportunity to secure low interest rates in the long term.
• Macroeconomic dynamics: Pay attention to core inflation and SNB communication. If the monetary authorities announce a tighter monetary policy, the window of opportunity for cheap fixed-rate mortgages is closing rapidly.

The personal risk profile: Your financial affordability

In the Swiss real estate market, a volatile SARON interest rate is the surest way to sleepless nights when the household budget is on edge. Although financial institutions check affordability with an imputed interest rate of usually 5%, the reality in wallets is different when rates rise.

Mandatory checks for homeowners

Make sure you review your financial figures and personal life situation in detail before making a decision:

• Free cash flow cushion: Could your household easily cushion a doubling of monthly mortgage interest rates over two years without drastically reducing living standards? If not, a fixed-rate mortgage is the more rational choice.
• affordability margin: The banks' rule of thumb is that total housing costs (interest, service charges, amortization) should not amount to more than a third of gross income. With SARON, you should calculate with an additional safety margin of 1— 2%.
• Planning horizon: Will there be a career change, a family or retirement in the next few years? The more volatile living conditions, the more stable the financial foundation should be thanks to a fixed-rate mortgage.

Strategy instead of all-in: The tranche model

The era of “all-or-nothing” decisions in home financing is over. Smart borrowers use the flexibility of the Swiss banking system to minimize cluster risks when fixing interest rates.

Why splitting is better than speculation

Instead of leaving the entire loan amount in SARON or switching completely to a single fixed-rate mortgage, strategic splitting analyses how you can optimally mix terms and products.

• Risk diversification: Divide the mortgage into three tranches, for example: One third remains in SARON (for maximum flexibility and profit with falling interest rates), one third in a 5-year fixed-rate mortgage and a third in a 10-year fixed-rate mortgage.
• Smoothing interest rate risk: Due to staggered terms, the entire loan amount never expires at a historically bad time. You gain time to react to market changes.
• Flexibility when it comes to amortization: SARON mortgages often allow more flexible repayments than rigid fixed-rate mortgages. Splitting allows you to maintain some of this financial momentum.

Contractual and organizational details

In addition to pure market interest rates, the legal framework of Swiss banks plays a fundamental role so as not to make expensive mistakes when switching. In particular, the “exchange law” enshrined in the framework agreement can have significant differences.

An often underestimated point is the phase-out period for SARON products. Although it is a money market product, many Swiss banks bind their customers to framework terms of 3 to 5 years. Anyone who wants to switch to another bank within this framework period in order to accept a better fixed-rate mortgage offer risks a high early repayment penalty. Therefore, check carefully whether the exchange law only applies to fixed-rate mortgages from the current provider or whether there is real flexibility.

Conclusion: System beats gut feeling

Switching from a SARON mortgage to a fixed-rate mortgage in Switzerland is not just a game of chance, but the result of market monitoring and your own risk tolerance. Don't rely on regulars' table forecasts or the supposedly perfect “low interest rate.”

In summary, it can be stated that anyone who keeps an eye on the swap markets, reacts quickly when the interest rate differential narrows and cleverly tranches the mortgage, significantly minimizes their financing costs. Despite all strategic planning, you should initiate the exchange process approximately 6 to 12 months before the desired fixation date with your bank, as forward financing (forward mortgages) requires lead time. Stay pragmatic — the financial security of your home can be calculated with the right strategy.

Mortgage financing glossary

• SARON (Swiss Average Rate Night): The referenced overnight money rate for the Swiss franc, which is based on actual transactions made in the secured money market. It forms the basis for money market mortgages following the end of LIBOR.
• Swap rate (interest rate swap): The interest rate at which banks exchange fixed interest payments for variable interest payments. It is the most important leading indicator and the refinancing basis for fixed-rate mortgage terms.
• Early repayment penalty (penalty): The fee charged by the bank if a fixed-rate mortgage or a SARON framework term is canceled before the contractually agreed expiration date. It is calculated from the difference between the contract interest rate and the current reinvestment rate on the money market.