Are you asking about a loss from a sale in 2025, or a capital loss carryover from 2024?
If you sold something at a loss in 2025, you do not enter the capital loss directly. You enter information about the sale, including the proceeds and basis. TurboTax will calculate the loss and enter it on your tax return.
In either case, go to Federal Taxes > Wages & Income > Investment Income. To enter a sale click the Start button for "Stocks, Cryptocurrency, Mutual Funds, Bonds, Other." To enter a capital loss carryover click the Start button for "Capital Loss Carryover."
