What do you think?

I don't want to give advice to a eCommerce client regarding setting up a business, taxes etc. One of my clients built a brand in 2016 and is doing well this year. He did his own taxes for 2016 because he was a sole proprietor and he told me he broke even. Last year he quit his job and will be owing a lot of taxes because he made huge profits with his eCommerce brand this year.

When he sets up his LLC could the accountant register his business he created for March of 2016?