@TMH4438
TurboTax would have created Schedule D to show the capital loss carryover, even if you had no sales of securities. You have to carry over the loss every year, whether or not you have any market activity. The critical point was three years ago - the first year that you filed a tax return with no market activity. When you started your tax return for that year, did you transfer information from the previous year? You probably don't remember at this point. If you did transfer information, TurboTax would have picked up the capital loss from the previous year. If you did not transfer information, and did not enter the capital loss carryover manually, the loss was dropped, and there was no way for TurboTax to pick it up in subsequent years.
In any case, you can't just pop a three-year-old loss into your tax return this year. You have to recalculate your tax returns for each of the years where the loss is missing, starting with the earliest year, and carry the loss from year to year in order to correctly calculate the loss that carries over to the current year. It isn't necessarily reduced by $3,000 every year. You will have to file amended returns for all the years where the capital loss carryover was missing, in order to establish the correct loss carryover amount. You don't have to wait for the past-year amended returns to be processed before you file your current-year tax return, but you need the information from the recalculated past-year returns in order to correctly calculate the capital loss carryover to the current year.
If you have further questions, it would be easier to discuss if you tell us the specific years involved. What was the last year that you had a Schedule D with a loss? What were the years that you filed without Schedule D (and without any capital loss shown on your Form 1040)? What is the first year that you will be filing with investment sales again? Did you already file your 2019 tax return?
