No, it does not necessarily change the final result of the tax return since there are so many other factors. If you added it, and the amount you owe does not change, there is no need to amend your return. If the PMI is irrelevant, and you decide to NOT amend your return, I suggest you remove the adjustment you made so that the 2017 tax return in TurboTax is exactly as you filed it. (if you added it as an amended return, simply delete the amendment). This way when you pull the file over next year, it will be what you truly filed.
