TomK
Expert Alumni

After you file

Generally, you must file Form 1040X within three years from the date you filed your original tax return or within two years of the date you paid the tax, whichever is later. 

Right now, you can amend your tax returns for 2014, 2015 and 2016. After April 15, 2018, you can no longer amend your 2014 tax return.