Note that, most forms in Turbotax are currently unavailable or not ready to file, because it is too early in the season. Most if not all of the forms should be ready by January 31. Make sure to download and install the program updates as they come along (if using TT online, updates are automatic).
There should be no problem filing a form 1120-S for an S-corp by March 15. If for some reason the forms are still delayed in the tax program, you can get an extension.
In rare cases, the IRS will extend deadlines, but this only usually happens if there is a last minute retroactive tax law change that causes them to have to issue new forms and reprogram their computers.
