A business liability insurance does not cover all damages that may arise from working as a freelancer. If, for example, a mistake is made during a contractually agreed project, which in turn causes damage and costs for the client, the business liability insurance does not apply. It also does not apply for a hacked computer or the loss of data.
This is where a professional liability insurance comes in. It is more expensive than a business liability insurance, but includes job-specific risks and offers the highest possible protection. For some professions, e.g. for physicians, pharmacists, lawyers, financial investment brokers or engineers, this insurance is mandatory. However, it is also recommended for freelancers, as it can prevent a bankruptcy if the freelancer is at fault.