There's no hard and fast rule. That simply encourages people to do that number -1. Instead, the law in this instance is saying: If you're carrying on a business, you need to be licensed. If we think you are carrying on a business and you're not licensed, we may take you to court in an effort to prove that you are (the government has the onus of proof). However, if you're holding garage sales on more than 6 days a year then we can simply allege you're carrying on a business and it is up to you to prove in court that you're not (the person has the onus of proof).