Bottom line is, you can't using TurboTax on a MAC. To complete the 1120-S Corporate Tax Return requires TurboTax Business, which is not available online or for MACs. It's for the Windows platform only. Additionally, in the past MAC users have reported issues when using something such as BootCamp to run the Windows OS on their MACs, and that setup is just flat out not supported by TurboTax, unfortunately.