How can I file an Amended 1040-X for 2024 from my 2024 TurboTax online tax filing? I need to change from filing MFS to MFJ. I have the W-7 filled out. But how do I calculate the difference in tax between the two filing statuses? I had filed my return in early April 2025. Can TurboTax help me find the difference? Do I need to pay again for a desktop software, or can I use the online one since it was filed online?