I understand that Form 1045, Application for Tentative Refund must generally be filed within one year of the end of the tax year in which the NOL was generated.   So, for a NOL generated in 2020, the deadline to file the 1045 would have been 12/31/2021.

Does that deadline get extended out if you file a 2020 amended tax return?  I just completed a 2020 amended tax return for a client in Feb 2022.  Does anyone know if I can use that date as the date the return was filed and still file the Form 1045?

If Filing the 1045 is no longer an option, I can still file amended returns for the previous years to carry back the NOL, correct?  But, I could not go back and amend 2016 and 2017 using 1040-X could I?

Thanks in advance for any help/input!