At the very beginning of starting a return for 2016, it should ask you if you want to bring information in from 2015. But you are correct, it may have already fill in the fields from the old info. However, you can simply change each of the fields once you've started the new return by selecting the option to edit or change your information at each step you fill in. If you look at the top of the page, there are tabs - you can select the personal information (first tab) and update that information before you proceed with the rest of the tax information (such as income). You don't need to try to fix the 2015 return if you didn't file it - just correct the 2016 return as you go through it. It will be correct for the 2016 return, and for the following years as well.