If you used TurboTax last year, you are able to automatically import your tax information by logging into the same account that you used a year ago. If you want to review any information from last year's return you can click on the "Previous Taxes" button on the left side of the "Tax Home" screen when you log in.
If you did not use Turbotax, all you need is a few pieces of information from last year's return like your AGI, and your personal information to get started and be able to file in TurboTax.