I sold a rental property in 2015 for a significant loss. the loss exceeded my AGI (showing it as a negative number.) I did not claim a carry forward loss for 2016 because I did not realize the opportunity. Can I claim a carry forward loss for 2017? If so, is there an specific amount that I would have to claim? Also, since the loss on the 2015 return was the entire amount, would I have to go back and amend returns for 2015 and 2016 breaking up the total loss amounts (not a problem if it does cost me money or penalty)?