Here is a link to Publication 535, Business Expenses. It has links to various items. Some expenses are deductible, others are capitalized and depreciated, etc. It talks about various expenses. I highly suggest you take the time and read this. It should answer a lot of questions and help guide you in your specific situation.
https://www.irs.gov/publications/p535
https://www.irs.gov/pub/irs-pdf/p535.pdf
Also, is this a single member LLC? If so, did you incorporate or elect to be treated as a corporation? If single member and not incorporated or election to be treated as a corporation, it is a disregarded entity and you would file Sch C.
If elected to be a corporation, Form 1120, and if elected S status, Form 1120S.
If a multiple member LLC and not incorporated or elected to be treated as corporation, then it is a partnership and Form 1065 would be filed.
**Disclaimer: Effort has been made to offer correct information; but due to the discussion forum limitations, the poster disclaims any legal responsibility for the accuracy of the poster's response**
