Please explain ... you have 1 C-corp and an LLC ? Or did you register the LLC to be taxed as a C-corp?
Or do you have 2 separate businesses ?
To file the 1120 :
TT Business is for 1120 Corporation, 1120S Corp, 1065 Partnership or 1041 Estate/Trust returns and will not do your personal 1040 return. It is a separate program from Home & Business (or Personal & Small Business). Home & Business is for personal returns that include a schedule C for self employment or sole proprietor. A single owner LLC would be reported on Schedule C unless the LLC elected to be treated as an S corp or C corp.
If this is your first 1120 then I highly recommend you seek local professional assistance to get the first return done for the corp and get educated on the filing/payroll/dividend requirements for both the fed & state. Doing things wrong or not setting up your books correctly can cost you dearly in penalties down the road.
Turbo Tax Business is not available to do online or on a Mac. You can buy the Window's version here. And you can have both TT Business and TT Home & Business (or any personal version) installed on your computer at the same time.
https://turbotax.intuit.com/small-business-taxes
