DavidK
New Member

After you file

You have 3 years from the date you filed your 2017 return (or 2 years after you paid the tax due, whichever is later) to file an amended return, which means you don't have to amend your 2017 return before the 2018 filing deadline. More info

Depending on your situation, the first link and either the second or third link should help you: