Losses incurred in 2000 should have been reported on the 2000 return and the same for the 2008 losses. Any unallowed losses are carried forward and used up each tax year as allowed. You cannot skip the rules and apply the losses when you feel like it. So if you did not properly report the losses in the years they happened you may need to amend all the tax years affected to see if you have anything left over to carry to the 2020 return. Seek local professional assistance to see where you stand and if/how to correct this error.
