Can I carry over the remainder of a loss to my 2024 tax return? In 2023, I had a loss of $6257 (Line 16), but I was only able to claim $3,000 (Line 21) of it as a loss.

Yes.   If you transferred your prior return it should be already filled in.

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 the Start or Update button

You enter the full amount that carried over, not just the 3,000

Thank you! I didn't use Turbo Tax in for 2023 taxes so it wasn't automatically filled in.