Here is what I figured out to do. Open the clients 2020 return. Go to one of their W-2 forms (earned income) and temporarily change the amount in Box 1 so that the W-2 income for 2020 equals what the W-2 income is for 2021. You can do this on Schedule C or F by just upping the gross receipts by the difference between 2020 and 2021 income.

Then hit F9 to calculate (DO NOT HIT SAVE UNDER ANY CIRCUMSTANCES) and look at what the EIC and CTC amounts are now on the 2020 return. Those are the amounts that go on that stupid AL FIT form.

Write the amounts down and exit the return without saving it. Then go to the 2021 AL FIT form and fill in the blocks with the amounts and you are done. If they got zero, a zero goes in there.