If you are using a TurboTax Desktop program, you can do this by clicking on "File" that is in the top left of your TurboTax screen (in the black bar that goes across the very top of the screen (You will see File, Edit, View, Tools, Online and Help). To save the return you are in, you will select "File" then select "Save." To start a new return, you will select "File" and then "New Tax Return".
If you are using TurboTax Online it automatically saves your progress after every screen change and when you sign out. Make sure to select "Sign Out" when you exit your return.
To start a new tax return using TurboTax Online you will have to create another Online Account with a unique username.
For additional information:
How Do I Switch From TurboTax Online to TurboTax Desktop?
How many tax returns can I file with TurboTax?
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