I have this same situation -- filing MFJ for Federal, but only 1 spouse has any CA sourced income (as a non-resident for CA. Both spouses are NY residents).
So, I create a dummy Federal return with an MFS filing status, segregating out all income and deductions, for the spouse with the CA income. This then will create a CA non-resident return with MFS status for that spouse.
Now, when it comes to file, I have to paper file. As you have noted, I need to attach the "real" MFJ Federal return. However, then none of the numbers in the MFJ Federal return will match the Federal starting point in the CA MFS return -- CA requires you to start with the Federal return and show those numbers in the CA return.
So, is the solution to send in both the real MFJ Federal return and the dummy MFS Federal return, maybe with a cover letter explaining what is being done?
Thanks for the help in clarifying how this should work.
