According to article L. 441-6 of the French Code de commerce (Commercial code), penalties for late payment apply as of right, as from the date on which the payment was due.
The parties may not agree on late payment penalties in an amount less than three times the legal interest rate.
If no penalties were agreed, the penalties are calculated on the basis of the interest rate applied by the Central European Bank to its most recent refinancing transaction plus 10 percentage points.