I completed my 2024 return with the desktop version and would like to upload it to my online account. How can I do that?

You can upload documents to your TurboTax Online account after you sign into your account.   Click on Documents from the left side menu and upload your files.   You can upload receipts, forms and return copies, as a pdf and/or tax file.    You can upload 2025 docs at the end of the year.

When you use desktop download software,your tax return is stored on your own hard drive or on any backup device you use like a flash drive.  It is not stored in online account with TurboTax.   Only returns prepared using online TT software are stored in that online account.