When I had a business return I ran TurboTax and it was a pretty simple business, basically just recovering home office and travel expenses. When we had the store we had a professional accountant. These days we have a pretty simple return and I do it myself but by the time I get all the forms done I still spend 4 hours or so on it. (more if I sell some stock). I usually overpay enough that I get money back but it is better than owing with interest and penalties if I guess wrong.