As of 2013, creditors (the issuer of the invoice) have the right to charge an SEK 450 fee for late payment if the debtor is a business or authority. If the customer is a private individual the maximum fee may only be SEK 60. The fee can only be charged once per bill.
For each invoice you can activate automatic reminders to be sent out if the invoice passes its due date. You can also set default settings under Company settings → Invoice settings.
Late fee interest is something the can be added to invoices that have passed their due date. The earliest this interest can be added is 30 days efter the creation of the invoice. The interest rate will be updated for each day the invoice remains unpaid.
Late fee interest is regulated in Räntelagen (1975:635).