Greensleeves wrote:He timely filed his 2018 tax return and also timely made the election to carry forward the 2018 NOL.
This statement does not make any sense. Starting with the 2018 tax year NOL's could
only be carried forward. There was no carryback available, hence no election to be made. Then the CARES act came along in 2020 and changed the law to
require 2018, 2019, and 2020 NOL's to be carried back unless an election is made on the taxpayer's 2020 tax return (all of this is assuming a fiscal year taxpayer). So in your situation, the 2018 NOL must be carried back since your taxpayer cannot make an election to carryforward on a timely filed 2020 tax return solely because no extension was filed. Had he filed an extension he could still file 202 by 10/15 with the election to carryforward 2018, 2019, and/or 2020 NOL's.
There may be an exception here if the 2020 tax return is filed by 10/15 even without an extension. Something about regulatory vs. statutory elections and §301.9100...but this is above my pay grade.
For your next example of a taxpayer with a 2017 NOL, if he elected to carryforward the NOL then it will carryforward to 2018 first. Even though a return was not filed you must determine how much of the NOL was used, if any. Then carry to 2019, 2020, and so on. But this is far from your first example as the rules for 2017 NOL's are not the same as for 2018 - 2020.