@radbrad
Here’s the problem, and why I said to do things in the order that I suggested.
You can’t use form 1045 more than one year after the year that the loss occurred, that means your ability to use form 1045 for the 2016 refund ended December 31, 2018.
Suupose you file your 2015, 2016, and 2017 returns now. You can use the NOL to offset your tax on the 2017 return. Then you have to go back and file amended returns for 2015 and 2016 to carry back the NOL. If you have any loss left over, you can use that on your 2018 return.
You have no income or owe no tax for 2015, so the NOL won’t get used up, but you have to file to get it on paper.
Then, when you file the 2016 amended return, even though the NOL might generate a small refund, it won’t be paid because of the statute of limitations on amended returns, which applies regardless of the reason for the amendment. That means that if you owe tax for 2016, you will pay that tax when you file your return plus penalties and interest that could double the amount you owe. Then when you file the amended return with the NOL, you will get nothing back. However, if you include the NOL on your original 2016 return, it can zero out the tax that you owe, and if you owe no tax when you file a return, there is no penalty, even if the return is five years late.
