Separate fixed and variable costs
Start with twelve months of premiums for each household member. Add supplementary premiums separately. Then estimate eligible medical expenses and the portion you would pay yourself. Keep non-covered services in another line so they are not mistakenly included in the basic-insurance calculation.
Understand cost sharing
Ordinary adult cost sharing includes the deductible and usually 10% of eligible costs above it, with an annual retention-fee cap of CHF 700. Hospital contributions and some medicine rules differ; maternity and certain other services have exemptions. This means the deductible alone is not your maximum possible annual bill.
Stress-test the budget
Compare a low-use year with a year involving substantial treatment. Keep a reserve for bills arriving together rather than averaging every cost into a monthly figure. Use your personal quotes rather than a national average: a household decision needs the prices that apply to its own members and address.