@IRonMaN  The Curiosity Rule here at Intuit suggests that the reason for such amended returns be provided as a courtesy to those who will be left to wonder.  But perhaps you should refresh your memory on the statute of limitations on, for example, bad debts or foreign tax credit.  And of course, if 2017 taxes remain unpaid, an amended return can be filed for any reason.  

It could also be an NOL carryback arising from a later year, although that usually doesn't happen beyond five or six years.  Except for farmers, maybe.  Or is it fishermen?  Are we even allowed to use "fishermen" these days?  I'd have to look it up.