What is the default interest rate in Switzerland?

5% per year by law under Art. 104 para. 1 CO. If a higher contractual rate was agreed, it also applies during default. Between merchants, a higher rate may be charged if the usual bank discount rate at the place of payment exceeds 5%.

When does default interest start?

From the moment of default. As a rule that is the day after the reminder. If a specific due date was agreed, default occurs when it passes, without a reminder (Art. 102 CO). A payment term set unilaterally on the invoice is usually not an agreed due date.

Can I charge interest on default interest?

No. Under Art. 105 para. 3 CO, no default interest may be charged on default interest.

Can I also charge a reminder fee?

Only if it was agreed in advance, for example in your terms and conditions or on the quote. Without an agreement, only default interest can be enforced.

How many days per year are used?

Courts generally use actual days and 365 days per year. Banks and contracts often use the commercial method with 30 days per month and 360 days per year. The calculator supports both.

Swiss default interest calculator: 5% under Art. 104 CO

In short

Anyone who fails to pay a due invoice owes 5% interest per year from the moment of default (Art. 104 para. 1 CO), unless the contract says otherwise. Default begins with a reminder or, if a specific due date was agreed, when that date passes. Interest is claim × rate × days / 365.

How the default interest calculator works

Default interest is simple interest without compounding:

Default interest = claim × interest rate × interest days / days per year

The day default begins does not count; the payment or reference date does. For CHF 10,000 and 90 days of default at 5%, that is 10,000 × 5% × 90 / 365 = CHF 123.29.

Method	Interest days	Year	Used by
Actual / 365	actual calendar days	365 days	courts, debt collection
30 / 360	every month counts as 30 days	360 days	banks, many contracts

When does default begin?

Due and in default are not the same. An invoice is due as soon as it must be paid. Under Art. 102 CO, the debtor is only in default:

after a reminder, that is when you explicitly demand payment after the due date, or
without a reminder once an agreed due date has passed, for example «payable by 31 March» in the contract.

If the payment term only appears on your invoice without having been agreed, it is generally the reminder that triggers default. Enter the date on which default actually began.

Frequently asked questions

What is the default interest rate in Switzerland?: 5% per year by law under Art. 104 para. 1 CO. If a higher contractual rate was agreed, it also applies during default. Between merchants, a higher rate may be charged if the usual bank discount rate at the place of payment exceeds 5%.
When does default interest start?: From the moment of default. As a rule that is the day after the reminder. If a specific due date was agreed, default occurs when it passes, without a reminder (Art. 102 CO). A payment term set unilaterally on the invoice is usually not an agreed due date.
Can I charge interest on default interest?: No. Under Art. 105 para. 3 CO, no default interest may be charged on default interest.
Can I also charge a reminder fee?: Only if it was agreed in advance, for example in your terms and conditions or on the quote. Without an agreement, only default interest can be enforced.
How many days per year are used?: Courts generally use actual days and 365 days per year. Banks and contracts often use the commercial method with 30 days per month and 360 days per year. The calculator supports both.