Unless the partners are married and living in a community property state, the LLC files a separate partnership tax return form 1065. As part of preparing the 1065, each partner will get a K-1 statement that goes on their personal return, that lists their share of income and expenses. (It can be 50/50 or any other division as provided when the LLC was set up).
The partnership must have its own separate tax identification number (EIN, employer ID number). You can get it online in a few minutes. Most of the time, if the partnership changes, it needs a new EIN.
https://www.irs.gov/businesses/small-businesses-self-employed/apply-for-an-employer-identification-n.... Each partner's K-1 statement will be reported with their SSN or their ITIN.
To prepare a 1065, you need Turbotax Business. This is a separate program from Turbotax used to prepare personal returns, and is only available for PC, there is no Mac or online version. The deadline to file form 1065 (if you don't get an extension) is March 15, not April 15, and the late penalty is $195 per month per partner.
You may want to discuss your situation with a tax professional to help set up the partnership's books and the first year tax return so you know what to expect, then take over yourself for the future.
