My brother and I both use the TurboTax 2024 Standard desktop version. Between us, we do the tax returns for other family members. In past years, I was able to send him a copy of a file that I was working on, for his review. This was very helpful. This year, I sent him a *.tt24 file and he was able to open it. Afterward, I sent two other different files and he got an error message when trying to open them. (I am using TurboTax desktop with Windows 10 and VMWare, on my Macbook. He uses a PC.)