How is the early repayment penalty calculated for mortgages?

The 3-pillar calculation

The calculation of the early repayment penalty is based on the difference between the contractually agreed mortgage interest rate and the current reinvestment rate on the money market for the remaining term. The simplified formula is: Penalty = mortgage sum × interest difference × remaining term (in years). If the current market interest rate is significantly below your contract interest rate, the compensation is particularly high; if it is higher, many banks waive the penalty fee but rarely pay out the profit.

The mathematical core: The interest rate differential bridge

To understand the size of the penalty, you have to put yourself in the lender's position. When a bank grants you a mortgage, it often borrows the money itself on the capital market over the long term or ties up savings. If the mortgagee terminates the contract prematurely, the bank is sitting on these refinancing costs while the expected interest income is lost. The institution must now reinvest the recovered capital on the money and capital markets — and at the current conditions.

The decisive component is therefore the difference between your agreed contract interest rate and the rate at which the bank can reinvest the money. For example, if a property owner has taken out a 2.5 percent fixed-rate mortgage and the current rate for the remaining term is just 1.0 percent, the bank will incur an annual loss of 1.5 percent. This interest rate difference is extrapolated to the remaining years. With a loan amount of 800,000 francs and a remaining term of five years, this results in theoretical damage of 60,000 francs, which the bank claims as compensation.

The mystery of the reinvestment rate

The biggest point of contention when calculating is almost always the reinvestment rate applied by the bank. Customers often mistakenly assume that the bank simply passes on the money to a new mortgage customer at the current shop window interest rates. However, this is explicitly excluded in the general terms and conditions (GTC) of most Swiss institutions. Banks argue that they cannot guarantee that they will find a suitable borrower with the same term and credit rating on the same day.

Instead, the reinvestment rate is based on the so-called swap rate or the returns of Swiss Confederates (government bonds) with a corresponding maturity. These rates are generally significantly lower than interest rates for end customers. For you as a borrower, this means that the lower the general interest rate on the capital market, the lower the reinvestment rate is and the more expensive your early liquidation will be. Some banks even add an additional processing margin to this interbank rate, which further reduces the interest to be credited and artificially increases the fine payment.

Special scenarios: interest reversals and the prohibition of payouts of profits

The Swiss mortgage market has experienced considerable turbulence in recent years. A dynamic interest rate turnaround can radically change the calculation of the early repayment penalty. What happens if interest rates have risen sharply since you took out your fixed-rate mortgage? If your contract interest rate is 1.2 percent, but the current reinvestment rate for the remaining term is 2.0 percent, the bank will theoretically make a profit as a result of your termination. She can reinvest the money at a higher interest rate than you would have paid her.

In theory, the bank would have to pay you that profit. In practice in the Swiss financial world, however, this is an absolute rarity. Almost all credit institutions have included clauses in their contracts which state that a positive reinvestment deadline will not be paid out to the customer. In this scenario, the penalty is simply set to zero. It should also be noted: Should interest rates fall to extreme lows at the short end of the market, the reinvestment rate can become negative purely mathematically. During periods of historically low interest rates, this meant that customers had to pay even more than the actual interest rate difference.

Tactical exits and administrative background noises

Anyone who is confronted with high demands should not bury their heads in the sand. There are regulatory and contractual levers to limit the damage. The pure interest statement is only half the story; there is often a hefty processing fee for the administrative costs of early settlement, which can range between several hundred and a thousand francs.

An elegant way out is to buy a replacement or take over the mortgage by the buyer of the property. If you sell your property, the new owner may be required under the purchase agreement to take over the existing fixed-rate mortgage under the old conditions. The prerequisite for this is that the bank considers the buyer's creditworthiness to be sufficient after a sustainability check. Alternatively, many banks allow you to “move property”: You simply take the mortgage with you to your new property. In both cases, the expensive compensation is completely waived, as the credit agreement continues legally.

Conclusion: So check who binds himself forever

The early repayment penalty is the financial risk that is inseparably linked to the security of a fixed-rate mortgage. It protects the bank from market changes, but massively limits the homeowner's flexibility.

In summary, it can be stated that the calculation follows strict, mathematical rules in which the remaining term and the interest rate difference with the interbank market play the main roles. Since banks define the reinvestment rate in their favor, the costs of falling interest rates are immense. Anyone planning long-term financing should always prepare solid financial planning and take into account unforeseeable life events. If an exit is unavoidable, it is worthwhile trying to negotiate to transfer the mortgage to a buyer or transfer it to a new property in order to successfully escape the penalty trap.

Claim calculation glossary

• reinvestment rate: The interest rate at which a financial institution can invest the early repaid mortgage capital on the money and capital markets. It is usually based on swap rates.
• Contract interest: The interest rate fixed in the mortgage agreement that the borrower owes over the agreed term.
• Procurement of replacements: The legal and organizational process by which an existing mortgage is transferred to a new pledged property (a new property) in order to avoid early termination and the associated fines.