Thanks for asking your question! I'm sorry to hear about your tax issue and I'm going to try my best to help you understand or resolve it.
Thank you for your question and thanks for using JustAnswer.com. If your single member LLC is in the business of renting out real estate, you will use schedule E. If you are doing anything else, you will use Schedule C. The reason that the tax is so much different is self employment taxes. You do not have to pay self employment tax on rental income, but you do on everything else.
Please let me know if you need anything additional. Thanks again for using JustAnswer.com and have a great day.
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You should be aware that your question, as with most tax questions, can never really be answered completely...addressing all the permutations; that is because of the many assumptions that have to be made I have done my best to determine what I think you are asking and answering it in the most direct and understandable manner possible. If, however, after reviewing the questions, you have any uncertainties or further questions, please do not hesitate to ask.