Business & farm

The link posted by tagteam is helpful, but I will summarize it for you by answering your specific questions:

1. No, the 2020 farm NOL would have carried back to offset your taxable income reported in 2018 and 2019 to the extent the loss was large enough.  For example, if your 2018 AGI was $50,000 and your 2019 AGI was $50,000 and your 2020 farm loss was -$75,000, the loss is eliminated now because it offset all of 2018 income and half of 2019.  Since it has been more than 1 year after the due date of the carryback year, you will need to file Form 1040X for each carryback year to get your refund.
2. Again, since the carryback was not waived within 6 months of the due date of the return, you cannot carry this loss forward.  However, this loss would be applied to 2019 and 2020.  So, if my example above continues, there is only $25,000 AGI to be offset left from 2019.  If your 2021 loss was $50,000, it carries back and offsets the remaining AGI from 2019 and skips 2020 since there was no income (assuming you have no other source of income).  In this example, the remaining $25,000 loss in 2021 does carry forward and will be subject to the 80%-of-taxable-income limit.  You can include the application of the 2021 carryback to the Form 1040 X that would need to be filed due to the 2020 carryback.
   • The answer for 2a is N/A since the above answer is no
3. No, you needed to have filed the request for the waiver within 6 months after the original due date of filing the return.
4. Yes, you must include a waiver statement within 6 months after the original due date of filing the return.
   • Per the IRS to file the waiver:
     • To make this choice, attach a statement to your original return filed by the due date (including extensions) for the NOL year. This statement must show that you are choosing to waive the carryback period under section 172(b).  If you filed your original return on time but did not file the statement with it, you can make this choice on an amended return filed within 6 months of the due date of the return (excluding extensions). Attach a statement to your amended return, and write “Filed pursuant to section 301.9100-2” at the top of the statement. 

@zigzywno