Yes, you can save and come back when you are ready to complete your tax return. TurboTax Online automatically saves your work as you go through the interview. When you sign out, we'll make sure to save everything before we log you out. Just make sure that when you return to complete your return that you sign in with the same username and password that you used to start this return. 

I did use the same user name and password.  it said that I had to have the same password from 2016.  I don't know what that was.  I now have 2 usernames and passwords.  How can this be fixed?  I have paid for the deluxe.