First, you have to use the CD-version of the TurboTax software to be able to manually enter the data on Schedule C. For some strange reason, the downloadable version doesn't have this option - or at least it didn't in 2023. (Not sure if they'll fix that in the 2024 version)
As for TD Ameritrade -- I had accounts at both Schwab and TD Ameritrade and had no trouble transferring the data into the CD version of TurboTax last year. ... Of course, this year, all of my TD accounts have moved to Schwab under the merger, so I'll no longer need to transfer from TD.
So, I highly suggest you purchase the CD version of TurboTax. It's harder to find the CD version (everyone seems to sell the downloadable version instead). But the CD version offers a lot more features -- especially for those doing day trading. (I didn't choose mark to market either).
