I had a very difficult time this year with making TurboTax understand that our business partners split profits/losses at different percentages than our equity percentages. This seems like it would be very common, and TurboTax should be able to handle this situation easily. I had to do research and manually adjust the percentages while TurboTax was in "Form" mode.
It is hard to use without Tax knowladge - Why don't you provide the simple accounting module to book keeping the customized income / expense recording system which the customer keep recording the number whcih is the same format of the TurboTax input - Just add accumulable input fields whcih will be totalling at end of the year and at that time all tax report is done with some more data like w2, 1099, Div etc.
If you are filing business taxes for an LLC in the District of Columbia, there is no other choice than to file with this software. It is not as good a user interface as the online version, but the online version is not an option for small businesses in the District of Columbia. TurboTax, get it together and add District of Columbia to your business tax filing online software application. I had to borrow a friend's Windows PC to file my taxes with the desktop software because I only have Apple products for myself and my business.