So you didn't enter the carryover loss from 2019? And you already filed? You will have to amend your 2020 return to add it and to find out the right carryover to 2021. If it doesn't change your 2020 return you don't have to file the amended return. Did you have a current 2020 gain or loss on 1040 line 7?
Enter a Capital Loss Carryover under
Federal Taxes or Personal (Home & Business)
Wages and Income
Then scroll down to Investment Income
Capital Loss Carryovers - Click Start or Revisit
You have to report the carryover every year until it's used up. You can't skip a year. Even if you don't report it on your return you have to reduce it by the 3,000 (1,500 MFS) when you carry it over to next year. You can't choose when to use it.
This is from the IRS Pub 550 page 66 middle column Capital Loss Carryover:
"When you figure the amount of any capital loss carryover to the next year, you must take the current year's allowable deduction into account, whether or not you claimed it and whether or not you filed a return for the current year. "
Here is pub 550… http://www.irs.gov/pub/irs-pdf/p550.pdf
