Your buy in is considered a capital contribution and each year you will receive a K-1 that will need to be entered into TT.
The other part of LLC tax is that you need to maintain a basis schedule of your investment. This begins with your initial capital contribution and is updated annually by the applicable line on your K-1. This basis schedule is very important as it will be used to determine your overall gain or loss when you exit the LLC. It will also be necessary if the LLC passes out losses as you can only take losses to the extent of your basis.
Attached is a link to an IRS commentary on basis:
https://www.irs.gov/instructions/i1065sk1/ch01.html
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
