Swiss Mortgage for Foreigners: How the System Actually Works

The question expat buyers ask most often about Swiss mortgages is not about interest rates. It is: "The bank told me I cannot afford a CHF 900,000 apartment even though my salary is CHF 180,000 — how is that possible?" The answer lies in a mortgage system that was deliberately engineered to be conservative, and that uses rules entirely unlike anything found in the UK, the US, Australia, or most European markets.

Switzerland has one of the lowest mortgage default rates in the world — under 1%. That stability is not accidental. It is the direct result of strict FINMA regulations, a unique two-tranche debt structure, and an affordability test calculated against a hypothetical 5% interest rate rather than the actual prevailing rate. For expat buyers accustomed to banks that calculate borrowing capacity based on current rates, this requires a complete reset of expectations.

The 20% Down Payment Requirement

Swiss banks will finance a maximum of 80% of a residential property's appraised value. The buyer must provide 20% as equity. There is no mortgage insurance product that allows a lower deposit, and no equivalent of the UK's 5% or 10% first-time buyer schemes.

The composition of that 20% matters enormously. FINMA mandates that at least 10% of the property's total value must be "hard equity" — personal liquid cash, Pillar 3a (private pension) savings, inheritances, or proceeds from the sale of another property. This 10% hard equity requirement cannot be met using Pillar 2 (occupational pension) funds.

The remaining 10% can come from a broader range of sources, including a Pillar 2 advance withdrawal or pledge. But the first 10% must genuinely be your own unencumbered cash.

On a CHF 1,200,000 property:

• Minimum hard equity: CHF 120,000 (10%)
• Additional equity (can include Pillar 2): CHF 120,000 (10%)
• Maximum bank financing: CHF 960,000 (80%)
• Closing costs (3%–5%, not financeable): CHF 36,000–CHF 60,000

The total upfront cash requirement on a CHF 1.2 million purchase, when closing costs are included, typically falls between CHF 270,000 and CHF 300,000. This is the actual capital barrier most expats underestimate.

The Two-Tranche Mortgage Structure

Swiss mortgage debt is split into two distinct components with completely different repayment rules.

The First Mortgage (First Tranche)

The first tranche covers up to 65% of the property's appraised value (some banks use 66.67%). The defining feature of the Swiss first mortgage is that it does not require amortization. You are never legally obligated to repay this principal. You pay only the interest. Many Swiss homeowners carry first-tranche mortgage debt for thirty or forty years without ever reducing it.

This was historically a deliberate tax strategy: maintaining high mortgage interest payments provided ongoing deductions against the Eigenmietwert (imputed rental value). With the Eigenmietwert being abolished in 2029, that incentive diminishes, but the legal structure remains. Carrying permanent first-tranche debt is not inherently problematic — it simply means the debt continues for as long as you own the property unless you choose to repay it voluntarily.

The Second Mortgage (Second Tranche)

The second tranche covers the gap from 65% up to 80% of the property's value — the top 15% of bank financing. This tranche must be fully amortized (repaid) within 15 years, or by the time the primary earner reaches standard retirement age (65), whichever comes first.

The amortization can be calculated linearly, representing approximately 1% of total debt annually. On a CHF 180,000 second tranche (15% of CHF 1.2 million), the annual amortization requirement is approximately CHF 12,000 per year, or CHF 1,000 per month in addition to interest payments.

Amortization Methods: Direct vs. Indirect

Direct amortization means making regular principal repayments directly to the bank. Your loan balance decreases steadily, and your interest costs fall over time.

Indirect amortization is a distinctly Swiss approach. Instead of repaying the bank, you deposit the amortization amount into a Pillar 3a account that is pledged to the bank as collateral. The mortgage principal stays constant — the bank's lending risk is covered by the growing pension balance. Because the debt level does not decrease, you continue paying the same interest, which (until 2029) is fully deductible. The Pillar 3a contributions are simultaneously deductible from taxable income. When the account reaches the required amount, those funds are released to repay the second tranche in a lump sum.

Indirect amortization through Pillar 3a has been the standard advice for high-earning expats in Switzerland because it maximizes tax deductions on both the mortgage interest side and the pension contribution side. Whether it remains the optimal strategy post-2029 when mortgage interest deductibility disappears is a question worth modelling with a Swiss tax adviser before you commit to this structure.

The 5% Affordability Stress Test

This is the element that most surprises foreign buyers, and the source of the scenario described at the start of this article.

Swiss banks do not assess your mortgage affordability based on current market interest rates. As of mid-2026, SARON-based variable mortgage rates are available at approximately 1.0% to 1.5% all-in. Lenders offering five-year fixed rates can be found at around 1.4% to 2.0%. But none of these rates are used in the affordability calculation.

Instead, banks apply a regulatory stress test at a hypothetical rate of 5%, regardless of prevailing conditions. The rationale is systemic: if interest rates were to spike to 5% (as they have historically in Switzerland), the bank needs confidence that borrowers could continue servicing their debt without defaulting. This is the mechanism behind Switzerland's extremely low mortgage default rate.

The affordability formula the bank applies:

• Hypothetical annual interest: Total loan amount × 5%
• Annual second-tranche amortization: Second tranche amount ÷ 15 years
• Estimated annual maintenance: Purchase price × 1%

The sum of these three components must not exceed 33% of the borrower's gross annual household income (the "one-third rule").

A Worked Example

Assume you want to buy an apartment for CHF 1,000,000, financing 80% (CHF 800,000).

• First tranche (65%): CHF 650,000
• Second tranche (15%): CHF 150,000
• Hypothetical interest at 5%: CHF 800,000 × 5% = CHF 40,000
• Second tranche amortization over 15 years: CHF 150,000 ÷ 15 = CHF 10,000
• Annual maintenance at 1%: CHF 1,000,000 × 1% = CHF 10,000
• Total annual housing cost: CHF 60,000

For this to stay below 33% of gross income, the household requires gross annual income above CHF 182,000.

Two things follow from this. First, a single-income expat earning CHF 140,000 per year does not qualify for a CHF 1 million mortgage under this formula, even though current actual borrowing costs might easily be affordable at CHF 16,000 to CHF 20,000 per year. Second, dual-income households have a significant structural advantage — both incomes count toward the gross household figure.

Swiss banks also apply additional caution to variable income. Bonuses, RSUs, and foreign-sourced income are often discounted by 50% or more when calculating "sustainable" gross income. An expat with a CHF 120,000 base salary and a CHF 80,000 annual bonus may find only the base salary counts.

SARON vs. Fixed Rate: The Mortgage Product Decision

SARON Mortgages

SARON (Swiss Average Rate Overnight) replaced LIBOR in 2021 as the Swiss variable-rate mortgage benchmark. Following the Swiss National Bank's rate cuts in 2024 and 2025, the SNB policy rate sits at 0.00% as of mid-2026. The daily SARON rate currently hovers slightly negative, but lenders contractually floor the base rate at 0.00% for mortgage borrowers.

To the floored SARON base, the bank adds its margin — typically 0.7% to 1.1% depending on loan size and the borrower's creditworthiness. An expat with a strong balance sheet and a large loan might negotiate a 0.8% margin, resulting in an effective all-in rate of 0.8% in the current environment.

The mechanics of SARON billing are different from a standard variable rate. Interest is not calculated at a rate known at the start of the quarter. Instead, daily SARON rates are compounded retrospectively over the three-month billing cycle, and the total is charged at the end. You receive the invoice before you know the exact figure. For buyers accustomed to monthly statements with a fixed payment amount, this feels initially disorienting.

The practical advantage: SARON has historically been the cheapest Swiss mortgage product over long periods. The risk: if the SNB raises rates sharply, your quarterly bill increases within weeks. Most SARON contracts allow conversion to a fixed-rate product within one month's notice, which provides a useful exit valve.

Fixed-Rate Mortgages

Fixed-rate mortgages lock the interest rate for a defined term: typically 2, 3, 5, 7, 10, or 15 years. Five-year and ten-year terms are the most popular. The longer the term, the higher the rate — the bank is pricing its risk of a low-rate environment persisting.

Fixed rates provide absolute payment certainty. For expat households running tight budgets or with limited flexibility to absorb payment increases, this predictability has genuine value. The cost of that certainty is typically 0.3% to 0.6% higher than SARON in the current environment.

The significant danger with Swiss fixed-rate mortgages: early termination penalties. Breaking a fixed-rate mortgage before the term ends triggers a Vorfälligkeitsentschädigung — a prepayment penalty calculated based on the interest income the bank loses over the remaining term, often discounted to present value. On a large mortgage with several years remaining, this can run to tens of thousands of francs. If there is any material probability of selling the property or refinancing before your term expires, factor this cost into your decision.

Fixed-rate mortgages are generally portable within Switzerland — if you sell one property and buy another, you can transfer the mortgage rather than breaking it.

Which Product Is Right?

There is no universal answer. The conventional guidance: if you have a high risk tolerance, expect rates to stay low, and can absorb payment volatility, SARON provides the best expected long-term cost. If you value predictability, are stretching to meet the affordability test, or anticipate selling within the fixed term, a 5-year fixed rate at current levels provides reasonable certainty without excessive rate risk.

Many Swiss expat buyers split their financing: part on SARON, part on a medium-term fixed rate. This hedges some of the rate volatility without committing entirely to either structure.

The mortgage decision is one component of a larger purchase process. The Buying Property in Switzerland — Expat Guide covers the complete picture: Lex Koller permit eligibility, how to use Pillar 2 pension funds for your down payment, cantonal closing costs by canton, and the full transaction sequence from reservation deposit through to Grundbuch inscription.

Quick Reference: Swiss Mortgage Rules for Expats

See more Switzerland guides →