Does a bonus count towards income?

Only partly. A guaranteed 13th month's salary counts in full; variable bonuses are counted by many banks at half, or only as a multi-year average. The self-employed usually prove the average of the last two to three business years.

Do all banks calculate the same way?

The basic model is the same everywhere; the dials differ slightly: the imputed interest rate is 4.5 to 5 % depending on the bank, the limit 33 to 35 %. If you are close to the line, talk to several banks.

What about the second income?

When you buy together, both incomes count in full, as long as both of you are in the land registry and the loan agreement. Plan realistically for a reduced workload after children arrive: the bank calculates with today, your budget should calculate with tomorrow.

Huusfink Guide4 August 2026

Affordability made simple: how your bank calculates

Affordability decides whether you get a mortgage. The rule behind it is simpler than it sounds, and if you understand it, the meeting with the bank holds no surprises.

The rule in one sentence

Your annual housing costs, calculated the imputed way, may amount to at most one third of your gross household income. Imputed means: not at today's rate, but at a safety rate of 5 %.

The three cost blocks

→Imputed interest: 5 % on the whole mortgage. On a CHF 800'000 mortgage that is CHF 40'000 a year, whatever you actually pay.
→Maintenance and running costs: 1 % of the purchase price per year. Covers heating, insurance, fees and reserves for repairs.
→Amortisation: the mortgage above two thirds of the purchase price (the second mortgage) must be repaid within 15 years, at the latest by retirement.

An example

Purchase price CHF 1'000'000, equity CHF 200'000, household income CHF 150'000. The mortgage is CHF 800'000. Imputed interest: CHF 40'000. Maintenance: CHF 10'000. Amortising from CHF 800'000 down to CHF 650'000 over 15 years: CHF 10'000. Together CHF 60'000 a year, which is 40 % of the income. Result: not affordable, the bank declines, even though the real monthly costs at today's rates would be perfectly payable.

Why the 5 % makes sense

Mortgages run for decades, interest rates fluctuate. Borrow to the limit at rock-bottom rates and a rate rise forces you to sell, usually at the worst possible time. The 5 % is not an annoyance but your buffer. The Swiss rules come from the banks' self-regulation (the SBVg minimum requirements) and are recognised by FINMA.

When it gets tight: the three levers

→More equity: every additional franc lowers the mortgage, interest and amortisation at once. An advance on an inheritance or a gift counts too.
→A lower price: negotiating pays off especially with properties that have been listed for a long time. Find your personal price limit with the maximum purchase price calculator.
→A second income: buying together, with a partner's income counted in full, changes the calculation fundamentally.

Frequently asked questions

Work out your affordability directly: enter purchase price, income and equity, read off the traffic light.

Open the affordability calculator