The only complete way to switch names on your return is to start a new return. Since information in your tax returns goes with each name, you cannot just change the order of the names. Your return will keep getting rejected because the first SSN the IRS has is the first name on your 2018 return .
When you file your first tax return together, decide whose name should go first and then stick with it per the IRS 1040 instructions, which read:
"If you filed a joint return for 2018 and you are filing a joint return for 2019 with the same spouse, be sure to enter your names and SSNs in the same order as on your 2018 return."
