Minimum social security contribution on freelance income

In addition to my main (100%) job from which I earn a steady salary, I would like to take on freelance employment. I am curious as to how much I will have to deduct from my freelance income to cover social security payments.

I expect to earn around 2500 francs annually, which means that I have to register this self-employment at the cantonal social security office because it is more than the 2300-franc, non-declarable limit. I assume that I only need to contribute the equivalent of 5.223% of my income to AHV and IV (the amount levied on self-employed income below 17,200 francs). Am I correct?

Not really. The minimum annual social security contribution you can make is CHF 478. The lowest contribution rate of 5.223% applies to self employment which generates an income between CHF 9400 and CHF 17,200 per year. If you earn less than that amount, but more than CHF 2300, you have to pay a minimum social security payment of 478 Swiss francs per year.

While you may earn more than that from your day job, the social security office calculates your salary and freelance income separately. If you did not earn a salary and had multiple freelance jobs, on the other hand, your freelance income would be combined and you would pay the rate relevant to your entire income.

In your case, you would save money by taking on slightly less freelance work to keep your freelance income below CHF 2300.