What type of firms can I apply the late payment legislation to?
The legal status of the business you are seeking to claim interest from is irrelevant. It can be a sole proprietor, partnership or limited liability company. However you cannot apply the late payment legislation to personal debt.
What if a customer has more than one overdue invoice? How do I claim these multiple debts?
If each invoice relates to a separate order for goods or services, then you are entitled to claim interest and compensation on each overdue invoice. The amount of compensation that the legislation states that you can claim for varies with the size of the claim. Of course you have the option to add together several claims for compensation and late payment interest in one claim. If you do this, you should calculate each individually and set them out in writing so it is clear which claim relates to which order.