I am adding an expense that was missed on the 2017 1040. The taxpayer had an NOL so it does not change the liability for 2017, only the NOL C/F to 2018.  Do I have to amend the 2017 return or can I just reflect the change on the 2018 statements?  I believe CA allows you to just include a statement with the current year so I am hoping the IRS also allows this.  Please advise.